diff --git a/core/builtin_classes/file_object.py b/core/builtin_classes/file_object.py
index f8c1ca7..5fe2512 100644
--- a/core/builtin_classes/file_object.py
+++ b/core/builtin_classes/file_object.py
@@ -47,14 +47,14 @@ def read(self, ctx: Context) -> RTResult[Value]:
 
     @args([])
     @method
-    def readline(ctx):
+    def readline(self, ctx: Context):
         res = RTResult[Value]()
-        self = ctx.symbol_table.get("this")
         try:
             value = self.file.readline()
             return res.success(String(value))
         except OSError as e:
-            return res.failure(RTError(None, None, f"Could not read from file: {e.strerror}", None))
+            pos = Position(-1, -1, -1, "<idk>", "<idk>")
+            return res.failure(RTError(pos, pos, f"Could not read from file: {e.strerror}", ctx))
 
     @args([])
     @method
diff --git a/core/builtin_classes/string_object.py b/core/builtin_classes/string_object.py
index 9029551..f87c478 100644
--- a/core/builtin_classes/string_object.py
+++ b/core/builtin_classes/string_object.py
@@ -118,15 +118,15 @@ def endswith(self, ctx: Context) -> RTResult[Value]:
             )
         return res.success(Boolean(self.value.endswith(string.value)))
 
-    @args(["string"], [String("")])
+    @args(["string"], [String(" ")])
     @method
     def split(self, ctx: Context) -> RTResult[Value]:
         res = RTResult[Value]()
-        string = ctx.symbol_table.get("string")
+        string = ctx.symbol_table.get("string")  # String object
         assert string is not None
         if not isinstance(string, String):
             return res.failure(RTError(string.pos_start, string.pos_end, "Cannot split a non-string", string.context))
-        return res.success(Array([String(i) for i in self.value.split(string.value)]))
+        return res.success(Array([String(i) for i in self.value.split(str(string))]))
 
     @args(["string"], [String("")])
     @method
diff --git a/examples/args_test.rn b/examples/args_test.rn
index 0fc5cc0..cb6f64f 100755
--- a/examples/args_test.rn
+++ b/examples/args_test.rn
@@ -1,6 +1,6 @@
-import Argparser
+import argparser
 
-parser = Argparser.Argparser()
+var parser = argparser.Argparser()
 parser.add_flag("--version", "-v", "Show version")
 parser.add_named("--output", "Output file")
 parser.add_pos_opt("filename", "File")
diff --git a/examples/arrays.rn b/examples/arrays.rn
index c187c00..511720b 100755
--- a/examples/arrays.rn
+++ b/examples/arrays.rn
@@ -1,13 +1,13 @@
-import Array
+import array
 
-arr = Array.Array([1,2,3,4,5,6,7,8,9,10])
+const arr = array.Array([1,2,3,4,5,6,7,8,9,10])
 arr.append(11)
 print(arr.to_string())
 
 arr.pop(0)
 print(arr.to_string())
 
-print(arr.len())
+print(len(arr))
 
 arr.extend(["this", "is", "a", "array"])
 print(arr.to_string())
diff --git a/examples/classes.rn b/examples/classes.rn
index 9391c25..fa62024 100755
--- a/examples/classes.rn
+++ b/examples/classes.rn
@@ -9,10 +9,10 @@ class Person {
 }
 
 print("Enter a name, or type 'exit' to quit.")
-inp = input("Name: ")
+var inp = input("Name: ")
 
 while inp != "exit" {
-	p = Person(inp)
+	var p = Person(inp)
 	print(p.Format())
 	inp = input("Name: ")
 	p.single_line()
@@ -30,6 +30,6 @@ class Some {
     fun to_object() -> "Name is : "+ this.name + " Value is : "+ str(this.value)
 }
 
-cls_ = Some()
-obj = cls_.to_object()
+var cls_ = Some()
+var obj = cls_.to_object()
 print(obj)
diff --git a/examples/colors_test.rn b/examples/colors_test.rn
index 3fd78aa..5d46377 100755
--- a/examples/colors_test.rn
+++ b/examples/colors_test.rn
@@ -1,58 +1,58 @@
-import Colorlib
+import colorlib
 
 # Print colored text to the console using the colorlib library
-print(Colorlib.white("My name is John Doe"))
-print(Colorlib.red("My name is John Doe"))
-print(Colorlib.green("My name is John Doe"))
-print(Colorlib.yellow("My name is John Doe"))
-print(Colorlib.blue("My name is John Doe"))
-print(Colorlib.purple("My name is John Doe"))
-print(Colorlib.cyan("My name is John Doe"))
-print(Colorlib.gray("My name is John Doe"))
-print(Colorlib.black("My name is John Doe"))
-print(Colorlib.bgWhite("My name is John Doe"))
-print(Colorlib.bgRed("My name is John Doe"))
-print(Colorlib.bgGreen("My name is John Doe"))
-print(Colorlib.bgYellow("My name is John Doe"))
-print(Colorlib.bgBlue("My name is John Doe"))
-print(Colorlib.bgPurple("My name is John Doe"))
-print(Colorlib.bgCyan("My name is John Doe"))
-print(Colorlib.bgGray("My name is John Doe"))
-print(Colorlib.bgBlack("My name is John Doe"))
-print(Colorlib.bold("My name is John Doe"))
-print(Colorlib.italic("My name is John Doe"))
-print(Colorlib.underline("My name is John Doe"))
-print(Colorlib.inverse("My name is John Doe"))
-print(Colorlib.hidden("My name is John Doe"))
-print(Colorlib.strikethrough("My name is John Doe"))
-print(Colorlib.blackBright("My name is John Doe"))
-print(Colorlib.redBright("My name is John Doe"))
-print(Colorlib.greenBright("My name is John Doe"))
-print(Colorlib.yellowBright("My name is John Doe"))
-print(Colorlib.blueBright("My name is John Doe"))
-print(Colorlib.purpleBright("My name is John Doe"))
-print(Colorlib.cyanBright("My name is John Doe"))
-print(Colorlib.whiteBright("My name is John Doe"))
-print(Colorlib.bgBlackBright("My name is John Doe"))
-print(Colorlib.bgRedBright("My name is John Doe"))
-print(Colorlib.bgGreenBright("My name is John Doe"))
-print(Colorlib.bgYellowBright("My name is John Doe"))
-print(Colorlib.bgBlueBright("My name is John Doe"))
-print(Colorlib.bgPurpleBright("My name is John Doe"))
-print(Colorlib.bgCyanBright("My name is John Doe"))
-print(Colorlib.bgWhiteBright("My name is John Doe"))
-print(Colorlib.reset("My name is John Doe"))
-print(Colorlib.bold("My name is John Doe"))
-print(Colorlib.italic("My name is John Doe"))
-print(Colorlib.underline("My name is John Doe"))
-print(Colorlib.inverse("My name is John Doe"))
-print(Colorlib.hidden("My name is John Doe"))
-print(Colorlib.strikethrough("My name is John Doe"))
-print(Colorlib.bgReset("My name is John Doe"))
-print(Colorlib.bgBoldBright("My name is John Doe"))
+print(colorlib.white("My name is John Doe"))
+print(colorlib.red("My name is John Doe"))
+print(colorlib.green("My name is John Doe"))
+print(colorlib.yellow("My name is John Doe"))
+print(colorlib.blue("My name is John Doe"))
+print(colorlib.purple("My name is John Doe"))
+print(colorlib.cyan("My name is John Doe"))
+print(colorlib.gray("My name is John Doe"))
+print(colorlib.black("My name is John Doe"))
+print(colorlib.bgWhite("My name is John Doe"))
+print(colorlib.bgRed("My name is John Doe"))
+print(colorlib.bgGreen("My name is John Doe"))
+print(colorlib.bgYellow("My name is John Doe"))
+print(colorlib.bgBlue("My name is John Doe"))
+print(colorlib.bgPurple("My name is John Doe"))
+print(colorlib.bgCyan("My name is John Doe"))
+print(colorlib.bgGray("My name is John Doe"))
+print(colorlib.bgBlack("My name is John Doe"))
+print(colorlib.bold("My name is John Doe"))
+print(colorlib.italic("My name is John Doe"))
+print(colorlib.underline("My name is John Doe"))
+print(colorlib.inverse("My name is John Doe"))
+print(colorlib.hidden("My name is John Doe"))
+print(colorlib.strikethrough("My name is John Doe"))
+print(colorlib.blackBright("My name is John Doe"))
+print(colorlib.redBright("My name is John Doe"))
+print(colorlib.greenBright("My name is John Doe"))
+print(colorlib.yellowBright("My name is John Doe"))
+print(colorlib.blueBright("My name is John Doe"))
+print(colorlib.purpleBright("My name is John Doe"))
+print(colorlib.cyanBright("My name is John Doe"))
+print(colorlib.whiteBright("My name is John Doe"))
+print(colorlib.bgBlackBright("My name is John Doe"))
+print(colorlib.bgRedBright("My name is John Doe"))
+print(colorlib.bgGreenBright("My name is John Doe"))
+print(colorlib.bgYellowBright("My name is John Doe"))
+print(colorlib.bgBlueBright("My name is John Doe"))
+print(colorlib.bgPurpleBright("My name is John Doe"))
+print(colorlib.bgCyanBright("My name is John Doe"))
+print(colorlib.bgWhiteBright("My name is John Doe"))
+print(colorlib.reset("My name is John Doe"))
+print(colorlib.bold("My name is John Doe"))
+print(colorlib.italic("My name is John Doe"))
+print(colorlib.underline("My name is John Doe"))
+print(colorlib.inverse("My name is John Doe"))
+print(colorlib.hidden("My name is John Doe"))
+print(colorlib.strikethrough("My name is John Doe"))
+print(colorlib.bgReset("My name is John Doe"))
+print(colorlib.bgBoldBright("My name is John Doe"))
 
-# chaining multiple styles and Colorlibs combined multiple times
-print(Colorlib.bold(Colorlib.bgPurple(Colorlib.white("My name is John Doe"))))
-print(Colorlib.italic(Colorlib.bgRed(Colorlib.green("My name is John Doe"))))
-print(Colorlib.underline(Colorlib.bgYellow(Colorlib.blue("My name is John Doe"))))
-print(Colorlib.inverse(Colorlib.bgBlue(Colorlib.yellow("My name is John Doe"))))
+# chaining multiple styles and colorlibs combined multiple times
+print(colorlib.bold(colorlib.bgPurple(colorlib.white("My name is John Doe"))))
+print(colorlib.italic(colorlib.bgRed(colorlib.green("My name is John Doe"))))
+print(colorlib.underline(colorlib.bgYellow(colorlib.blue("My name is John Doe"))))
+print(colorlib.inverse(colorlib.bgBlue(colorlib.yellow("My name is John Doe"))))
diff --git a/examples/files.rn b/examples/files.rn
index 0122400..34cab54 100644
--- a/examples/files.rn
+++ b/examples/files.rn
@@ -1,15 +1,14 @@
-
-const f = File("examples/files.rn")
-const contents = f.read()
-f.close()
-f.is_closed()
+const f1 = File("examples/files.rn")
+const contents = f1.read()
+f1.close()
+f1.is_closed()
 
 print(contents)
 
 print("-------------")
 
-f = File("examples/files.rn")
-print(f.readline())
-print(f.readlines())
+const f2 = File("examples/files.rn")
+print(f2.readline())
+print(f2.readlines())
 
-f.close()
+f2.close()
diff --git a/examples/functions.rn b/examples/functions.rn
deleted file mode 100755
index 6f03e14..0000000
--- a/examples/functions.rn
+++ /dev/null
@@ -1,31 +0,0 @@
-# This is a very useful piece of software
-
-fun oopify(prefix) -> prefix + "oop"
-
-fun join(elements, separator)
-    result = ""
-    length = arrlen(elements)
-
-    for i = 0 to length then
-        result = result + elements/i
-        if i != length - 1 then result = result + separator
-    end
-
-    return result
-end
-
-fun map(elements, func)
-    new_elements = []
-
-    for i = 0 to arrlen(elements) then
-        append(new_elements, func(elements/i))
-    end
-
-    return new_elements
-end
-
-print("Greetings universe!")
-
-for i = 0 to 5 then
-    print(join(map(["l", "sp"], oopify), ", "))
-end
diff --git a/examples/hashmap.rn b/examples/hashmap.rn
index 0ced516..5c3d7a5 100644
--- a/examples/hashmap.rn
+++ b/examples/hashmap.rn
@@ -1,13 +1,13 @@
 # HashMap data type in Radon
 
-hashmap = {
+var hashmap = {
     "name": "John",
     "age": 23,
     "address": "123 Main St"
 }
 print(hashmap)
 
-value = hashmap["name"]
+var value = hashmap["name"]
 print(value)
 
 hashmap["bcd"] = 234
@@ -16,7 +16,7 @@ hashmap["abc"] = 456
 print(hashmap)
 
 while true {
-    key = input("Enter key: ")
+    var key = input("Enter key: ")
     if key == "exit" {break}
     print(hashmap[key])
 }
diff --git a/examples/import_test.rn b/examples/import_test.rn
deleted file mode 100755
index 1bf23e8..0000000
--- a/examples/import_test.rn
+++ /dev/null
@@ -1,48 +0,0 @@
-##################################
-# Testing stdlib Math library
-##################################
-
-# require("Math")
-
-# math = Math()
-# print(math.PI) # Ligal
-
-# print(Math().PI) # Illigal
-
-
-##################################
-# Testing System library
-##################################
-
-# require("System")
-
-# sys = System()
-# print(sys.getInfo())
-
-
-##################################
-# Testing external library
-##################################
-
-# require("simple.rn")
-
-
-##################################
-# Testing String library
-##################################
-
-# require("String")
-
-#!
-import String
-
-data = "Hello World !"
-str = String.String(data)
-
-print(str.len())
-
-!#
-import Math
-
-print(Math.PI) # Ligal
-
diff --git a/examples/io-test.rn b/examples/io-test.rn
index 63c538d..3520d19 100644
--- a/examples/io-test.rn
+++ b/examples/io-test.rn
@@ -12,5 +12,17 @@ print(str_val)
 var password = io.Input.get_password("Enter a password: ")
 print(password)
 
-var val = input("Enter a value: ")
-io.Output.write(val, sep="\n")
+var val = null
+var vals = []
+print("Type 'exit' to stop.")
+
+while val != "exit" {
+    val = input("Enter a value: ")
+    arr_append(vals, val)
+}
+
+print("unpacking is not implemented yet.")
+io.Output.write(vals, sep="\n")
+
+print("after unpacking, the result will be like this.")
+io.Output.write("dsf", "sdf", "sdf", "sdf", "sdf", "exit", sep="\n")
diff --git a/examples/json_testing.rn b/examples/json_testing.rn
index 8777351..a1efbca 100644
--- a/examples/json_testing.rn
+++ b/examples/json_testing.rn
@@ -1,7 +1,7 @@
-f = File("examples/posts.json", "r")
+var f = File("examples/posts.json", "r")
 
-json = Json()
-posts = json.loads(f.read())
+var json = Json()
+var posts = json.loads(f.read())
 f.close()
 
 assert arr_len(posts) == 100
diff --git a/examples/loops.rn b/examples/loops.rn
index 252d2e1..14ad44a 100755
--- a/examples/loops.rn
+++ b/examples/loops.rn
@@ -18,17 +18,19 @@ for i in [1, 2, 3, 4, 5] {
     print(i)
 }
 
+#! Comment starts from here
 for i in [1, 2, 3, 4, 5] {
     if i == 3 {
-        break
+        break # it is exiting the program; not just the loop it self.
     }
     print(i)
 }
-
+!#
 
 # While loop
-#!
-while i < 10 {
-    print(i)
-    i = i + 1
+
+var j = 11
+while j < 15 {
+    print(j)
+    j += 1
 }
diff --git a/examples/new_syntax.rn b/examples/new_syntax.rn
index aa17a6f..f412f77 100755
--- a/examples/new_syntax.rn
+++ b/examples/new_syntax.rn
@@ -1,69 +1,65 @@
 # PASSED
-# class Num {
-#     
-#     fun Num() {
-#         print("Num")
-#     }
-# 
-#     fun is_even(number) {
-#         if number % 2 == 0 {
-#             return true
-#         } else {
-#             return false
-#         }
-#     }
-# 
-# }
-# 
-# fun main() {
-#     num = Num()
-#     print(num.is_even(2))
-#     
-# }
-# 
-# main()
+class Num {
+    
+    fun __constructor__() {}
+
+    fun is_even(number) {
+        if number % 2 == 0 {
+            return true
+        } else {
+            return false
+        }
+    }
+}
+
+fun main() {
+    var num = Num()
+    print(num.is_even(2))
+}
+
+main()
 
 
 # PASSED
-# for i = 0 to 10 step 2 {
-#     print(i)
-# }
+for i = 0 to 10 step 2 {
+    print(i)
+}
 
 # PASSED
-# while true {
-#     usr = input("> ")
-#     if usr == "exit" {
-#         break
-#     }
-#     print(usr)
-# }
+while true {
+    var usr = input("> ")
+    if usr == "exit" {
+        break
+    }
+    print(usr)
+}
 
 # PASSED 
-# if 3 == 4 {
-#     print("OK")
-# 
-# } elif 3 == 0 {
-#     print("YES")
-#     
-# } else {
-#     print("NO")
-# }
+if 3 == 4 {
+    print("OK")
+
+} elif 3 == 0 {
+    print("YES")
+    
+} else {
+    print("NO")
+}
 
 # PASSED
-# fun something() -> true
-# a = fun () -> print("this is")
-# a()
+fun something() -> true
+var a = fun () -> print("this is")
+a()
 
 ############################################
 
 
-# FAILING
-# obj = {
-#     "name" : "John",
-#     "age"  : 30,
-#     "city" : "New York"
-# }
+# PASSED
+var obj = {
+    "name" : "John",
+    "age"  : 30,
+    "city" : "New York"
+}
 
-# i = 3
-# i += 4
-# print(i)
+var j = 3
+j += 4
+print(j)
diff --git a/examples/operator_overloading.rn b/examples/operator_overloading.rn
index 2405261..a832e87 100644
--- a/examples/operator_overloading.rn
+++ b/examples/operator_overloading.rn
@@ -21,12 +21,12 @@ class WrongOp {
     }
 }
 
-a = WrongOp(69)
+var a = WrongOp(69)
 a.dump("a")
-b = WrongOp(420)
+var b = WrongOp(420)
 b.dump("b")
 
-c = a + b
+var c = a + b
 c.dump("a + b")
-d = a - b
+var d = a - b
 d.dump("a - b")
diff --git a/examples/operators-bug.rn b/examples/operators-bug.rn
deleted file mode 100644
index ab956a1..0000000
--- a/examples/operators-bug.rn
+++ /dev/null
@@ -1,12 +0,0 @@
-x = 5
-y = 2
-
-x /= y
-print(x) # 2.5 OK as floor division.
-
-x //= y
-print(x) # 1.0 Failed as Integer division
-
-assert 5 / 5 == 1.0 # 1.0 OK as floor division.
-
-assert 5 // 5 == 1 # Invalid Syntax: Token cannot appear after previous tokens
\ No newline at end of file
diff --git a/examples/os_examples.rn b/examples/os_examples.rn
index e46ace3..8979ca5 100644
--- a/examples/os_examples.rn
+++ b/examples/os_examples.rn
@@ -11,8 +11,8 @@ print(is_dir)
 
 var list_dir = os.listdir("tests")
 print(list_dir)
-# print(arr_len(list_dir))
+print(len(list_dir))
 
-# for file in list_dir {
-#     print(file)
-# }
\ No newline at end of file
+for file in list_dir {
+    print(file)
+}
\ No newline at end of file
diff --git a/examples/pyapi_advanced.rn b/examples/pyapi_advanced.rn
index bca9f53..d602804 100644
--- a/examples/pyapi_advanced.rn
+++ b/examples/pyapi_advanced.rn
@@ -1,5 +1,7 @@
+## This is an example of how to use the `pyapi()` `BuiltInFunction` in Radon
+## Syntax: pyapi("python code", namespace HashMap{}) -> load all variables to namespace, which is accessable by Radon later on.
 
-ns = {}
+var ns = {}
 
 ns["cb"] = fun(x, y) -> (x + y) * 101
 
@@ -12,10 +14,10 @@ def my_func(x, y):
 print(f'Return value (from Radon function in Python): {cb(34, 35)}')
 ", ns)
 
-func = ns["my_func"]
+var func = ns["my_func"]
 
 print("func is: " + print_ret(func))
 
-ret = func("hello", "world")
+var ret = func("hello", "world")
 print("Return value (from Python function in Radon): " + str(ret))
 
diff --git a/examples/python_api.rn b/examples/python_api.rn
deleted file mode 100755
index 791bb70..0000000
--- a/examples/python_api.rn
+++ /dev/null
@@ -1,27 +0,0 @@
-## This is an example of how to use the `pyapi()` `BuiltInFunction` in Radon
-## Syntax: pyapi("python code") -> String (output of the python code)
-
-ns = {}
-
-pyapi("import os; cwd = os.getcwd()", ns)
-print("Current working directory: " + ns["cwd"])
-
-pyapi("import os; files = os.listdir()", ns)
-print("Files in current directory: " + str(ns["files"]))
-
-pyapi("import math; pi = math.pi", ns)
-print("Value of pi: " + ns["pi"])
-
-pyapi("sum_ = 2 + 2", ns)
-print("Sum of 2 + 2: " + ns["sum_"])
-
-ns["x"] = x = 6
-ns["y"] = y = 7
-
-pyapi("sum_ = x + y", ns)
-print("Sum of "+str(x)+" + "+str(y)+": " + ns["sum_"])
-
-ns["xs"] = xs = [1, 2, 3, 4, 9]
-
-pyapi("sum_ = sum(xs)", ns)
-print("Sum of "+str(xs)+": " + ns["sum_"])
diff --git a/examples/requests_test.rn b/examples/requests_test.rn
index 963cc2c..b4efd7f 100644
--- a/examples/requests_test.rn
+++ b/examples/requests_test.rn
@@ -1,16 +1,16 @@
 # API testing
 
-request = Requests()
-json = Json()
+var request = Requests()
+var json = Json()
 
 # get request to the API
-# response_get = request.get("https://jsonplaceholder.typicode.com/posts")
+# var response_get = request.get("https://jsonplaceholder.typicode.com/posts")
 
 # print(response_get)
 # print(type(response_get))
 # print(response_get.status_code)
 
-# radon_object = json.loads(response_get)
+# var radon_object = json.loads(response_get)
 
 # print(type(radon_object))
 # print(arr_len(radon_object))
@@ -20,34 +20,34 @@ json = Json()
 # }
 
 # post request to the API
-# response_post = request.post("https://jsonplaceholder.typicode.com/posts", {"title": "foo", "body": "bar", "userId": 1})
+# var response_post = request.post("https://jsonplaceholder.typicode.com/posts", {"title": "foo", "body": "bar", "userId": 1})
 # print(response_post)
 # print(type(response_post))
-# radon_object = json.loads(response_post)
+# var radon_object = json.loads(response_post)
 # print(radon_object)
 # print(type(radon_object))
 
 
 # put request to the API
-# response_put = request.put("https://jsonplaceholder.typicode.com/posts/1", {"id": 1, "title": "foo", "body": "bar", "userId": 1})
+# var response_put = request.put("https://jsonplaceholder.typicode.com/posts/1", {"id": 1, "title": "foo", "body": "bar", "userId": 1})
 # print(response_put)
 # print(type(response_put))
-# radon_object = json.loads(response_put)
+# var radon_object = json.loads(response_put)
 # print(radon_object)
 # print(type(radon_object))
 
 # delete request to the API
-# response_delete = request.delete("https://jsonplaceholder.typicode.com/posts/1")
+# var response_delete = request.delete("https://jsonplaceholder.typicode.com/posts/1")
 # print(response_delete)
 # print(type(response_delete))
-# radon_object = json.loads(response_delete)
+# var radon_object = json.loads(response_delete)
 # print(radon_object)
 # print(type(radon_object))
 
 # patch request to the API
-# response_patch = request.patch("https://jsonplaceholder.typicode.com/posts/1", {"title": "foo"})
+# var response_patch = request.patch("https://jsonplaceholder.typicode.com/posts/1", {"title": "foo"})
 # print(response_patch)
 # print(type(response_patch))
-# radon_object = json.loads(response_patch)
+# var radon_object = json.loads(response_patch)
 # print(radon_object)
 # print(type(radon_object))
diff --git a/examples/scoping.rn b/examples/scoping.rn
index 74f905e..5f3ed46 100755
--- a/examples/scoping.rn
+++ b/examples/scoping.rn
@@ -1,8 +1,8 @@
 # NOTE: this is supposed to fail
-m = 69
+var m = 69
 if true {
-    y = 420
-    m = y + m
+    var y = 420
+    var m = y + m
     print(m)
 }
 print(m)
diff --git a/examples/simple-grep.rn b/examples/simple-grep.rn
index 9c8bc41..8772f8c 100644
--- a/examples/simple-grep.rn
+++ b/examples/simple-grep.rn
@@ -1,40 +1,40 @@
-import Argparser
+import argparser
 
 fun main() {
-    parser = Argparser.Argparser()
+    var parser = argparser.Argparser()
     parser.add_flag("--help", "-h", "Show this help text and exit")
     parser.add_pos_opt("query", "String to query", required=true)
     parser.add_pos_opt("file", "File to query string in", required=true)
     parser.add_flag("--line-numbers", "-n", "Show line numbers")
     parser.add_named("--max-lines", "Maximum amount of lines to show", conversor=int)
-    args = parser.parse(argv[:])
+    var args = parser.parse(argv[:])
 
     if args["--help"] {
         print(parser.usage(argv[0]))
         exit()
     }
 
-    f = File(args["file"], "r")
-    lines = (String(f.read())).split("\n")
+    var f = File(args["file"], "r")
+    var lines = (String(f.read())).split("\n")
     f.close()
 
-    matched_lines = []
-    i = 0
+    var matched_lines = []
+    var i = 0
     for line in lines {
         if args["query"] in line {
             arr_append(matched_lines, [i, line])
         }
-        nonlocal i++
+        i++
     }
 
     if not is_null(args["--max-lines"]) {
-        nonlocal matched_lines = matched_lines[:args["--max-lines"]]
+        var matched_lines = matched_lines[:args["--max-lines"]]
     }
 
     for line in matched_lines {
-        s = line[1]
+        var s = line[1]
         if args["--line-numbers"] {
-            nonlocal s = args["file"] + ":" + line[0] + ": " + s
+            var s = args["file"] + ":" + line[0] + ": " + s
         }
         print(s)
     }
diff --git a/examples/simple.rn b/examples/simple.rn
index 35d9db3..e2b6926 100755
--- a/examples/simple.rn
+++ b/examples/simple.rn
@@ -2,26 +2,34 @@
 # Linear search algorithm
 fun find(list, value) {
     for i = 0 to len(list) {
-        if i == value {
+        if list[i] == value {
             return i
         }
     }
     return -1
 }
 
-# list = [1, 2, 3, 4, 5]
-# index = find(list, 3)
-# print(index)
+var list = [1, 2, 3, 4, 5]
+var index = find(list, 3)
+print(index)
 
-fun iseven(num) -> if (num%2) == 0 { print("even") } else { print("odd") }
+fun iseven(num) -> if (num % 2) == 0 { return true } else { return false } # returning null !!
+print(iseven(234))
+print("iseven(42): " + str(iseven(42)))
+print("iseven(2341): " + str(iseven(2341)))
 
 class Algorithm {
+    fun __constructor__(){} # without constructor class is raiseing function is not defined.
+
     fun find(list, value) {
         for i = 0 to len(list) {
-            if i == value {
+            if list[i] == value {
                 return i
             }
         }
         return -1
     }
-}
\ No newline at end of file
+}
+
+var algo = Algorithm()
+print(algo.find(list, 3))
diff --git a/examples/slicing.rn b/examples/slicing.rn
index 968c19d..dca91c4 100755
--- a/examples/slicing.rn
+++ b/examples/slicing.rn
@@ -1,35 +1,34 @@
 # Slicing
 
 # Array of Numbers slicing
-my_arr = [1,2,3,4,5,6,7,8,9,0]
-print(my_arr[0])
-print(my_arr[0:5])
-print(my_arr[0:9:2])
-# print(my_arr[])
-# print(my_arr[-1])
+var my_nums_array = [1,2,3,4,5,6,7,8,9,0]
+print(my_nums_array[0])
+print(my_nums_array[0:5])
+print(my_nums_array[0:9:2])
+print(my_nums_array[-1])
 
 # Array of Strings slicing
-my_str_arr = ["This", "is", "an", "example", "string"]
-print(my_str_arr[0])
-print(my_str_arr[0:3])
-print(my_str_arr[0:5:2])
-# print(my_str_arr[])
+var my_str_array = ["This", "is", "an", "example", "string"]
+print(my_str_array[0])
+print(my_str_array[0:3])
+print(my_str_array[0:5:2])
+print(my_str_array[-5])
+print(my_str_array[-5:-1])
+print(my_str_array[-5:-1:2])
 
 # Complex Array slicing
-my_complex_arr = [1, "This", 2, "is", 3, "an", 4, "example", 5, "string", 4.64, 2.4556, 324.2345]
-print(my_complex_arr[0])
-print(my_complex_arr[11])
-print(my_complex_arr[0:9:1])
-print(my_complex_arr[0:10:2])
-# print(my_complex_arr[])
+var my_complex_array = [1, "This", 2, "is", 3, "an", 4, "example", 5, "string", 4.64, 2.4556, 324.2345]
+print(my_complex_array[0])
+print(my_complex_array[11])
+print(my_complex_array[0:9:1])
+print(my_complex_array[0:10:2])
 
 # String slicing
-my_str = "This is an example string"
+var my_str = "This is an example string"
 
 print(my_str[0:4:1])
 print(my_str[5:7])
 print(my_str[9])
-# print(my_str[])
 
 # Straight forward slicing
 print("string"[0:3])
@@ -37,11 +36,11 @@ print([1,2,3,4,5,6,7,8,9,0][0:5])
 
 
 # updating values in array
-my_arr = [1,2,3,4,5,6,7,8,9,0]
-my_arr[0] = 10
-print(my_arr)
+var my_array_test = [1,2,3,4,5,6,7,8,9,0]
+my_array_test[0] = 10
+print(my_array_test)
 
 # updating values in string
-my_str = "This is an example string"
-new_str = my_str[19] = "S"
-print(new_str)
+var my_str_test = "This is an example string"
+var new_str_test = my_str_test[19] = "S"
+print(new_str_test)
diff --git a/examples/syntax.rn b/examples/syntax.rn
index 4ef210f..0292233 100755
--- a/examples/syntax.rn
+++ b/examples/syntax.rn
@@ -31,12 +31,12 @@
 # ^= - Exponentiation and assign
 
 # Variable definition
-a = 10
-b = 20
+var a = 10
+var b = 20
 print(a + b) # 30
 
-c = "Hello"
-d = "World"
+var c = "Hello"
+var d = "World"
 print(c + " " + d) # Hello World
 
 # Conditional statement
@@ -49,7 +49,7 @@ if a > b {
 }
 
 # For loop
-x = 9 # Multiplication table of 9
+var x = 9 # Multiplication table of 9
 
 for i = 1 to 11 {
     print(str(x) + " X " + str(i) + " = " + str(x * i))
@@ -58,7 +58,7 @@ for i = 1 to 11 {
 # While loop
 while x > 0 {
     print(x)
-    x = x - 1
+    x -= 1
 }
 
 # Function definition
@@ -69,7 +69,7 @@ fun add(a, b) {
 print(add(10, 20)) # 30
 
 # Anonymous function
-sub = fun (a, b) {
+var sub = fun (a, b) {
     return a - b
 }
 
@@ -82,7 +82,7 @@ print(mul(10, 20)) # 200
 # Class definition
 class Person {
     # Constructor
-    fun Person(name, age) {
+    fun __constructor__(name, age) {
         this.name = name
         this.age = age
     }
@@ -97,6 +97,6 @@ class Person {
 }
 
 # Use a class
-person = Person("Almas", 21)
-details = "Name is : " + person.get_name() + ", Age : " + str(person.get_age())
+var person = Person("Almas", 21)
+var details = "Name is : " + person.get_name() + ", Age : " + str(person.get_age())
 print(details)
diff --git a/radon.py b/radon.py
index 7a68faa..d4f144a 100755
--- a/radon.py
+++ b/radon.py
@@ -18,6 +18,7 @@
     pass
 
 import core as base_core
+from core.colortools import Log
 from core.parser import Context
 from core.lexer import Position
 
@@ -133,8 +134,13 @@ def main(argv: list[str]) -> None:
     base_core.global_symbol_table.set("argv", base_core.radonify(argv, pos, pos, Context("<global>")))
     if source_file is not None:
         head, _ = os.path.split(source_file)
-        with open(source_file, "r") as f:
-            source = f.read()
+        try:
+            with open(source_file, "r") as f:
+                source = f.read()
+        except FileNotFoundError:
+            print(Log.deep_error(f"[!] FileNotFound: {Log.deep_error(source_file, bold=True)}"))
+            exit(1)
+
         (result, error, should_exit) = base_core.run(source_file, source, import_cwd=head)
 
         if error:
diff --git a/stdlib/array.rn b/stdlib/array.rn
index 9719190..d944cbf 100644
--- a/stdlib/array.rn
+++ b/stdlib/array.rn
@@ -16,10 +16,10 @@ class Array {
     fun append(item) -> arr_append(this.list, item)
     fun pop(index) -> arr_pop(this.list, index)
     fun extend(list) -> arr_extend(this.list, list)
-    fun find(index) -> arr_find(this.list, index)
+    fun find(index) -> (this.list)[index]
     fun slice(start, end) -> ((this.list)[start:end])
     
-    fun __len__() -> arr_len(this.list)
+    fun __len__() -> len(this.list)
     fun is_empty() -> this.list == []
     fun to_string() -> str(this.list)
     fun is_array() -> true
diff --git a/stdlib/os.rn b/stdlib/os.rn
index 142bb1d..4a856d0 100644
--- a/stdlib/os.rn
+++ b/stdlib/os.rn
@@ -215,29 +215,3 @@ class _Path {
 
 var path = _Path
 
-
-class Test
-{
-    var property1 = "Hello, World!"
-
-    fun __constructor__()
-    {
-
-    }
-
-    fun func1(arg1, arg2=true)
-    {
-        "Description for func1"
-    }
-
-    fun func2(arg1=null)
-    {
-        "Description for func2"
-        return true
-    }
-
-    fun no_description() {
-        return null
-    }
-}
-
diff --git a/test.py b/test.py
index 953dc57..0c18ebe 100755
--- a/test.py
+++ b/test.py
@@ -40,7 +40,7 @@ def run_tests(directory: str = "tests") -> int:
         ["mypy", "."], stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=dict(**os.environ, MYPY_FORCE_COLOR="1")
     )
 
-    failed_tests = []
+    failed_tests: list[str] = []
     for test in os.listdir(directory):
         json_file = f"{directory}/{test}.json"
         if not test.endswith(".rn"):
@@ -85,7 +85,7 @@ def run_tests(directory: str = "tests") -> int:
         return 1
 
 
-def record_tests(directory="tests") -> int:
+def record_tests(directory: str = "tests") -> int:
     for test in os.listdir(directory):
         if not test.endswith(".rn"):
             continue