code: def _sorted(dict_):
      try:
          return sorted(six.iterkeys(dict_))
      except TypeError:
          invalidInputError(
              False, "nest only supports dicts with sortable keys."
          )
  
file_path: BigDL/python/dllib/src/bigdl/dllib/utils/nest.py
imports: import six
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 8 for calling a global function with example usage: _sorted(dict_) and returns: sorted