code: def forward(self, inputs):
      xp = backend.get_array_module(*inputs)
      y, t = inputs
      # flatten
      y = y.ravel()
      t = t.ravel()
      c = y >= 0
      count = xp.maximum(1, (t != self.ignore_label).sum())
      return (xp.asarray((c == t).sum() / count, dtype=y.dtype),)
  
file_path: chainer/chainer/functions/evaluation/binary_accuracy.py
imports: from __future__ import division
  from chainer import backend
  from chainer import function
  from chainer.utils import type_check
label_desc: Use image node_id 2 for calling the BinaryAccuracy obj's underlying member method code with example usage: obj.forward(inputs) and returns: xp