old_contents: #!/usr/bin/env python
  
  from origin import OriginData
  
  class Var(OriginData):
  
      tag_name = 'var'
      def __init__(self, id, start_value):
          super(Var, self).__init__()
          self.name = id
          self.start_value = start_value
  
new_contents: #!/usr/bin/env python
  
  from origin import OriginData
  
  class Var(OriginData):
  
      tag_name = 'var'
      def __init__(self, id, value):
          super(Var, self).__init__()
          self.id = id
          self.value = value
  
subject: change varibles from self.name to self.id and from self.start_value in self.value