code: def make_charset(letters):
      return (
          "["
          + CS_ESCAPE.sub(lambda m: "\\" + m.group(), "".join(letters))
          + "]"
      )
  
file_path: catboost/contrib/python/Pygments/py2/pygments/regexopt.py
imports: import re
  from re import escape
  from os.path import commonprefix
  from itertools import groupby
  from operator import itemgetter
label_desc: Use image node_id 1 for calling a global function with example usage: make_charset(letters) and returns: unknown