code: def setUp(self):
      a_shape = self._set_shape([self.m, self.k], self.transa)
      b_shape = self._set_shape([self.k, self.n], self.transb)
      c_shape = self._set_shape([self.m, self.n], False)
      self.c_dtype = numpy.result_type(self.a_dtype, self.b_dtype)
      self.a = _setup_tensor(0.5, 1, a_shape, self.a_dtype, 0.75)
      self.b = _setup_tensor(0.5, 1, b_shape, self.b_dtype, 0.75)
      self.gc = _setup_tensor(-1, 1, c_shape, self.c_dtype)
      self.gga = _setup_tensor(0.5, 1, a_shape, self.a_dtype)
      self.gga[numpy.where(self.a < 0.75)] = 0
      self.ggb = _setup_tensor(0.5, 1, b_shape, self.b_dtype)
      self.ggb[numpy.where(self.b < 0.75)] = 0
      self.forward_answer = self._matmul(self.a, self.b)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import cuda
  import chainer.functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling the TestCooMatMul obj's underlying member method code with example usage: obj.setUp() without return types