class_docstr: Base class of pooling function over a set of 2d planes.
class_docstr_tok: ["Base","class","of","pooling","function","over","a","set","of","2d","planes","."]
code: def _get_pool_mode(self):
      raise NotImplementedError()
  
file_path: chainer/chainer/functions/pooling/pooling_2d.py
imports: from chainer.backends import cuda
  from chainer import function_node
  from chainer.utils import collections_abc
  from chainer.utils import conv
  from chainer.utils import type_check
label_desc: Use image node_id 5 for calling the Pooling2D obj's underlying member method code with example usage: obj._get_pool_mode() without return types