code: def is_nested(values):
      '''Check if values is composed only by iterable elements.'''
      return (all(isinstance(item, Iterable) for item in values)
              if isinstance(values, Iterable) else Falsef is_nested(values):
      '''Check if values is composed only by iterable elements.'''
      return (all(isinstance(item, Iterable) for item in values)
              if isinstance(values, Iterable) else False)
docs: Check if values is composed only by iterable elements.