code: def _as_mat(x):
      if x.ndim == 2:
          return x
      return x.reshape(len(x), -1)
  
imports: import unittest
  import numpy
  import six
  import chainer
  from chainer.backends import cuda
  from chainer import gradient_check
  from chainer.initializers import constant
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling a global function with example usage: _as_mat(x) and returns: x, x