code: def _relu(x):
      expected = x.copy()
      for i in numpy.ndindex(x.shape):
          if x[i] < 0:
              expected[i] = 0
      return expected
  
imports: import numpy
  import chainer.functions
  from chainer import testing
  from chainer.testing import backend
label_desc: Use image node_id 1 for calling a global function with example usage: _relu(x) and returns: expected