code: def id_unique(dict_id, name, lineno):
      
      if dict_id in name_dict:
          global error_occurred
          error_occurred = True
          print(
              "ERROR - {0:s} definition {1:s} at line {2:d} conflicts with {3:s}"
              .format(name, dict_id, lineno, name_dict[dict_id]))
          return False
      else:
          return True
docs: Returns True if dict_id not already used.  Otherwise, invokes error