code: def get_model_url_base_from_env():
      """
      Returns a value of environment variable ``NNABLA_MODELS_URL_BASE`` if set,
      otherwise returns ``None``.
      """
      return os.environ.get("NNABLA_MODELS_URL_BASE", None)
  
imports: from __future__ import absolute_import
  import os
  from nnabla import logger
  from nnabla.utils.download import get_data_home
label_desc: Use image node_id 2 for calling a global function with example usage: get_model_url_base_from_env() and returns: os