class_docstr: Indexer mixin
  
  Mixin for handling indexers.
  
  .. note::
     To use this mixin the instance inheriting it must set the
      ``indexer`` or ``indexers`` attribute in ``__init__`` (not both).
docstr: Flag for existence of indexer
docstr_tok: ["Flag","for","existence","of","indexer"]
code: def __indexer__(self):
      """Flag for existence of indexer"""
      return hasattr(self, "indexer") or hasattr(self, "indexers")
  
imports: import warnings
  from abc import abstractmethod
  import numpy
  from ._base_functions import check_stack, check_params
  from ..None import config
  from ..utils.exceptions import ParallelProcessingError
  from ..externals.sklearn.base import clone, BaseEstimator
label_desc: Use image node_id 1 for calling the IndexMixin obj's underlying member method code with example usage: obj.__indexer__() and returns: unknown