code: def get_argument_parser(parser=None):
      
      if parser is None:
          parser = argparse.ArgumentParser()
  
      # Store globally to be able to warn the user about the fact he's probably wrong not to pass a parser to
      # parse_args(), later.
      global _parser
      _parser = parser
  
      _parser.add_argument("--default-env-file", "-E", action="append")
      _parser.add_argument("--default-env", action="append")
      _parser.add_argument("--env-file", action="append")
      _parser.add_argument("--env", "-e", action="append")
  
      return _parser
docs: Creates an argument parser with arguments to override the system environment.
  
      :api: bonobo.get_argument_parser
  
      :param _parser:
      :return: