code: def setUp(self):
      self.x = numpy.random.uniform(-1, 1, (4, 2, 3)).astype(self.dtype)
      self.t = numpy.array([[0, 1], [1, 0]]).astype(numpy.int32)
      self.l = numpy.array([[2, 0, 2, 1, 2], [2, 1, 2, 0, 2]]).astype(
          numpy.int32
      )
      self.blank_symbol = 2
      self.x_length = numpy.full(
          (len(self.x[0]),), len(self.x), dtype="i"
      )
      self.l_length = numpy.full(
          (len(self.t),), len(self.t[0]), dtype="i"
      )
      self.use_length = True
      if self.reduce == "mean":
          self.gy = numpy.random.uniform(-1, 1, ()).astype(self.dtype)
      else:
          self.gy = numpy.random.uniform(-1, 1, (2,)).astype(self.dtype)
  
      if self.dtype == numpy.float16:
          self.check_forward_options = {"atol": 1e-2}
          self.check_backward_options = {
              "atol": 1e-3,
              "dtype": numpy.float64,
          }
      else:
          self.check_forward_options = {}
          self.check_backward_options = {"atol": 1e-4}
  
imports: import math
  import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  from chainer import functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer.testing import condition
label_desc: Use image node_id 1 for calling the CTCTestBase obj's underlying member method code with example usage: obj.setUp() without return types