code: def update_nested_dict(main_dict, new_dict):
      """Update nested dict (only level of nesting) with new values.
  
      Unlike dict.update, this assumes that the values of the parent dict are
      dicts (or dict-like), so you shouldn't replace the nested dict if it
      already exists. Instead you should update the sub-dict.
      """
      # update named styles specified by user
      for name, rc_dict in six.iteritems(new_dict):
          if name in main_dict:
              main_dict[name].update(rc_dict)
          else:
              main_dict[name] = rc_dict
      return main_dict
  
file_path: catboost/contrib/python/matplotlib/py2/matplotlib/style/core.py
imports: from __future__ import absolute_import, division, print_function
  import six
  import os
  import re
  import contextlib
  import warnings
  import matplotlib
  from matplotlib import rc_params_from_file, rcParamsDefault
label_desc: Use image node_id 11 for calling a global function with example usage: update_nested_dict(main_dict, new_dict) and returns: main_dict