old_contents: import six
  
  from sevenbridges.meta.resource import Resource
  from sevenbridges.meta.fields import StringField
  
  
  class Breakdown(Resource):
      """
      Breakdown resource contains price breakdown by storage and computation.
      """
      storage = StringField(read_only=True)
      computation = StringField(read_only=True)
  
      def __str__(self):
          return six.text_type(
              '<Breakdown: storage={storage}, computation={computation}>'.format(
                  storage=self.storage, computation=self.computation
              )
          )
  
new_contents: import six
  
  from sevenbridges.meta.resource import Resource
  from sevenbridges.meta.fields import StringField
  
  
  class Breakdown(Resource):
      """
      Breakdown resource contains price breakdown by storage and computation.
      """
      storage = StringField(read_only=True)
      computation = StringField(read_only=True)
      data_transfer = StringField(read_only=True)
  
      def __str__(self):
          if self.data_transfer:
              return six.text_type(
                  '<Breakdown: storage={storage}, computation={computation}, '
                  'data_transfer={data_transfer}>'.format(
                      storage=self.storage, computation=self.computation,
                      data_transfer=self.data_transfer
                  )
              )
          return six.text_type(
              '<Breakdown: storage={storage}, computation={computation}>'.format(
                  storage=self.storage, computation=self.computation
              )
          )
  
subject: Add data_transfer to price breakdown