code: def _get_keys_with_empty_values(grp):
      """Find mapping keys where values have length zero.
  
      Helper for `_filter_groups`, which is in turn a helper for `group_files`.
      Given a mapping key -> Collection[Any], return the keys where the length of the
      collection is zero.
  
      Args:
          grp (Mapping[Any, Collection[Any]]): dictionary to check
  
      Returns:
          set of keys
      """
      empty = set()
      for k, v in grp.items():
          if (
              len(v) == 0
          ):  # explicit check to ensure failure if not a collection
              empty.add(k)
      return empty
  
imports: from __future__ import annotations
  import logging
  import os
  import pathlib
  import pickle
  import warnings
  from datetime import datetime, timedelta
  from functools import total_ordering
  import yaml
  from yaml import UnsafeLoader
  from satpy._config import config_search_paths, get_entry_points_config_dirs, glob_config
  from .yaml_reader import AbstractYAMLReader
  from .yaml_reader import load_yaml_configs
label_desc: Use image node_id 6 for calling a global function with example usage: _get_keys_with_empty_values(grp) and returns: empty