docs: def dfa_json_importer(input_file: str) -> dict:
      """ Imports a DFA from a JSON file.
  
      :param str input_file: path + filename to json file;
      :return: *(dict)* representing a DFA.
      """
      file = open(input_file)
      json_file = json.load(file)
  
      transitions = {}  # key [state ∈ states, action ∈ alphabet]
      #                   value [arriving state ∈ states]
      for (origin, action, destination) in json_file['transitions']:
          transitions[origin, action] = destination
  
      dfa = {
          'alphabet': set(json_file['alphabet']),
          'states': set(json_file['states']),
          'initial_state': json_file['initial_state'],
          'accepting_states': set(json_file['accepting_states']),
          'transitions': transitions
      }
      return dfa