code: def fontset_choice(arg):
      return directives.choice(arg, ["cm", "stix", "stixsans"])
  
file_path: catboost/contrib/python/matplotlib/py2/matplotlib/sphinxext/mathmpl.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import hashlib
  import os
  import sys
  import warnings
  from docutils import nodes
  from docutils.parsers.rst import directives
  import sphinx
  from matplotlib import rcParams
  from matplotlib.mathtext import MathTextParser
label_desc: Use image node_id 1 for calling a global function with example usage: fontset_choice(arg) and returns: directives