code: def get_flattened_iterator(comp_ids, ngroups, levels, labels):
      # provide "flattened" iterator for multi-group setting
      mapper = _KeyMapper(comp_ids, ngroups, levels, labels)
      return [mapper.get_key(i) for i in range(ngroups)]
  
imports: import warnings
  import numpy
  from pandas._libs import algos, hashtable, lib
  from pandas._libs.hashtable import unique_label_indices
  from pandas.compat import PY3, long, string_types
  from pandas.core.dtypes.cast import infer_dtype_from_array
  from pandas.core.dtypes.common import ensure_int64, ensure_platform_int, is_categorical_dtype, is_list_like
  from pandas.core.dtypes.missing import isna
  import pandas.core.algorithms
label_desc: Use image node_id 9 for calling a global function with example usage: get_flattened_iterator(comp_ids, ngroups, levels, labels) and returns: unknown