code: def add_port_argument(
      parser: Union[argparse.ArgumentParser, argparse._ArgumentGroup]
  ) -> None:
      """Add an argument for port."""
      parser.add_argument(
          "-p",
          "--port",
          default=constants.DEFAULT_SERVER_PORT,
          type=int,
          help="Port to run the server at.",
      )
  
file_path: rasa/rasa/cli/arguments/run.py
imports: import os
  import argparse
  from typing import Union
  from rasa.cli.arguments.default_arguments import add_model_param, add_endpoint_param
  from rasa.core import constants
  from rasa.env import DEFAULT_JWT_METHOD, JWT_METHOD_ENV, JWT_SECRET_ENV, JWT_PRIVATE_KEY_ENV, AUTH_TOKEN_ENV
label_desc: Use image node_id 4 for calling a global function with example usage: add_port_argument(parser) without return types