old_contents: #!/usr/bin/env python
  
  from origin import OriginData
  
  class Image(OriginData):
  
      tag_name = 'image'
  
      def __init__(self, file_name):
          super(Image, self).__init__()
          self.file = file_name
  
new_contents: #!/usr/bin/env python
  
  from origin import OriginData
  
  class Image(OriginData):
  
      tag_name = 'img'
  
      def __init__(self, file_name):
          super(Image, self).__init__()
          self.file = file_name
  
subject: change value of class attribute tag_name from image to img