code: def setUp(self):
      self.link = links.PReLU(shape=(3,))
      W = self.link.W.data
      W[...] = numpy.random.uniform(-1, 1, W.shape)
      self.link.cleargrads()
  
      self.W = W.copy()  # fixed on CPU
  
      # Avoid unstability of numerical gradient
      self.x = numpy.random.uniform(0.5, 1, (4, 3, 2)).astype(
          numpy.float32
      )
      self.x *= numpy.random.randint(2, size=(4, 3, 2)) * 2 - 1
      self.gy = numpy.random.uniform(-1, 1, (4, 3, 2)).astype(
          numpy.float32
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import gradient_check
  from chainer import links
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
label_desc: Use image node_id 1 for calling the TestPReLUMulti obj's underlying member method code with example usage: obj.setUp() without return types