code: def crelu(x, axis=1):
      """Concatenated Rectified Linear Unit function.
  
      This function is expressed as follows
  
       .. math:: f(x) = (\\max(0, x), \\max(0, -x)).
  
      Here, two output values are concatenated along an axis.
  
      See: https://arxiv.org/abs/1603.05201
  
      Args:
          x (:class:`~chainer.Variable` or :ref:`ndarray`):
              Input variable. A :math:`(s_1, s_2, ..., s_N)`-shaped float array.
          axis (int): Axis that the output values are concatenated along.
              Default is 1.
  
      Returns:
          ~chainer.Variable: Output variable of concatenated array.
          If the axis is 1, A :math:`(s_1, s_2 \\times 2, ..., s_N)`-shaped float
          array.
  
      .. admonition:: Example
  
          >>> x = np.array([[-1, 0], [2, -3]], np.float32)
          >>> x
          array([[-1.,  0.],
                 [ 2., -3.]], dtype=float32)
          >>> y = F.crelu(x, axis=1)
          >>> y.array
          array([[0., 0., 1., 0.],
                 [2., 0., 0., 3.]], dtype=float32)
  
      """
      return CReLU(axis=axis).apply((x,))[0]
  
file_path: chainer/chainer/functions/activation/crelu.py
imports: import six
  import chainer
  from chainer import backend
  from chainer import function_node
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling a global function with example usage: crelu(x, axis) and returns: CReLU