code: def _get_default_metavar_for_optional(self, action):
      return ""
  
imports: import argparse
  import os
  from typing import Tuple
  from jina.enums import ProtocolType
  from jina.logging.predefined import default_logger
label_desc: Use image node_id 4 for calling the _ColoredHelpFormatter obj's underlying member method code with example usage: obj._get_default_metavar_for_optional(action) and returns: str