Add language api class init

Fix python args

Fix a typo for python tasks

Fix a typo for python printing

Fix a typo for python printing

examples/python_initialize.dig

@@ -0,0 +1,11 @@
+_export:
+  py:
+    require: tasks.initialize.InstanceVariable
+  arg1: var1
+  arg2: var2
+
++step1:
+  py>: tasks.initialize.InstanceVariable.step1
+
++step2:
+  py>: tasks.initialize.InstanceVariable.step2

examples/ruby_initialize.dig

@@ -0,0 +1,11 @@
+_export:
+  rb:
+    require: 'tasks/initialize'
+  arg1: var1
+  arg2: var2
+
++step1:
+  rb>: InstanceVariable.step1
+
++step2:
+  rb>: InstanceVariable.step2

examples/tasks/initialize.py

@@ -0,0 +1,17 @@
+import digdag
+
+class InstanceVariable:
+    def __init__(self, arg1):
+        self.arg1 = arg1
+
+    def step1(self):
+        print(self.arg1)
+        print(digdag.env.params['arg1'])
+        print(digdag.env.params['arg2'])
+        print('self.arg1 is modified!!!')
+        self.arg1 = 'var3'
+        print(self.arg1)
+
+    def step2(self):
+        print('Instance variables is initialized by each tasks.')
+        print(self.arg1)

examples/tasks/initialize.rb

@@ -0,0 +1,19 @@
+class InstanceVariable
+  def initialize(arg1)
+    @var = arg1
+  end
+
+  def step1
+    puts @var
+    puts Digdag.env.params['arg1']
+    puts Digdag.env.params['arg2']
+    puts '@var is modified!!!'
+    @var = 'var3'
+    puts @var
+  end
+
+  def step2
+    puts "Instance variables is initialized by each tasks."
+    puts @var
+  end
+end