code: def __call__(self, x):
      h1 = F.relu(self.l1(x))
      h2 = F.relu(self.l2(h1))
      return self.l3(h2)
  
imports: import mock
  import tempfile
  import pytest
  import chainer
  import chainer.links
  import chainer.functions
  from chainer.training import extensions
  from chainer.training import StandardUpdater
  from chainer.training import Trainer
  import chainermn
  from chainermn import create_communicator
  from chainermn.extensions import multi_node_snapshot
  from chainermn.extensions import _multi_node_snapshot
label_desc: Use image node_id 2 for calling the MLP obj's underlying member method code with example usage: obj.__call__(x) and returns: self