code: def is_key(k: Optional[str]) -> bool:
      """Returns True if the argument is a valid argparse optional arg input, False
      otherwise.
  
      Strings that start with - or -- are considered valid for now.
  
      """
      return k is not None and len(k) > 0 and k[0] == "-"
  
file_path: caliban/caliban/util/argparse.py
imports: import argparse
  import itertools
  import os
  from typing import Dict, List, Optional, Tuple
  from blessings import Terminal
  import caliban.util
  import caliban.util.fs
  import schema
label_desc: Use image node_id 5 for calling a global function with example usage: is_key(k) and returns: unknown