code: def _signature_str(function_name, arg_sig):
      """Helper function to output a function signature"""
      return "{}{}".format(function_name, arg_sig)
  
file_path: catboost/contrib/python/joblib/joblib/func_inspect.py
imports: import inspect
  import warnings
  import re
  import os
  import collections
  from itertools import islice
  from tokenize import open
  from .logger import pformat
label_desc: Use image node_id 4 for calling a global function with example usage: _signature_str(function_name, arg_sig) and returns: str