docs: def rename_afw_states(afw: dict, suffix: str):
      """ Side effect on input! Renames all the states of the AFW
      adding a **suffix**.
  
      It is an utility function used during testing to avoid automata to have
      states with names in common.
  
      Avoid suffix that can lead to special name like "as", "and",...
  
      :param dict afw: input AFW.
      :param str suffix: string to be added at beginning of each state name.
      """
      conversion_dict = {}
      new_states = set()
      new_accepting = set()
      for state in afw['states']:
          conversion_dict[state] = '' + suffix + state
          new_states.add('' + suffix + state)
          if state in afw['accepting_states']:
              new_accepting.add('' + suffix + state)
  
      afw['states'] = new_states
      afw['initial_state'] = '' + suffix + afw['initial_state']
      afw['accepting_states'] = new_accepting
  
      new_transitions = {}
      for transition in afw['transitions']:
          new_transition = __replace_all(conversion_dict, transition[0])
          new_transitions[new_transition, transition[1]] = \
              __replace_all(conversion_dict, afw['transitions'][transition])
      afw['transitions'] = new_transitions