code: def _flatten_list(elements):
      return [item for sublist in elements for item in sublist]
  
imports: from copy import copy
  from inspect import signature, _empty
  import re
  from collections.abc import Iterable
  from collections import defaultdict
  from itertools import product
  from six import string_types
label_desc: Use image node_id 13 for calling a global function with example usage: _flatten_list(elements) and returns: unknown