code: def resolve_format(fmt):
      if not fmt:
          return "table"
      elif isinstance(fmt, str) and fmt in _FORMATS:
          return fmt
      else:
          raise NotImplementedError(fmt)
  
imports: from collections import namedtuple
  import os.path
  import re
  import textwrap
  from c_common import tables
  from .None import REPO_ROOT
  from ._files import iter_header_files, iter_filenames
label_desc: Use image node_id 5 for calling a global function with example usage: resolve_format(fmt) and returns: str, fmt