old_contents: #!/usr/bin/env python
  """
  :Author Patrik Valkovic
  :Created 22.08.2017 11:37
  :Licence GNUv3
  Part of grammpy-transforms
  
  """
  
  from grammpy import *
  
  
  def remove_unit_rules(grammar: Grammar, transform_grammar=False) -> Grammar:
      raise NotImplementedError()
new_contents: #!/usr/bin/env python
  """
  :Author Patrik Valkovic
  :Created 22.08.2017 11:37
  :Licence GNUv3
  Part of grammpy-transforms
  
  """
  
  from typing import List
  from grammpy import *
  
  class ReducedUnitRule(Rule):
      by_rules = []  # type: List[Rule]
      end_rule = None  # type: Rule
  
  
  def remove_unit_rules(grammar: Grammar, transform_grammar=False) -> Grammar:
      raise NotImplementedError()
subject: Add ReducedUnitRule class