code: def vector(self):
      a = chainer.Variable(
          input_generator.positive_increasing(
              2,
          )
      )
      b = chainer.Variable(
          input_generator.nonzero_increasing(
              2,
          )
          * 0.3
      )
      return (a, b)
  
imports: import chainer
  import chainer.functions
  from chainer import testing
  from chainer.testing import attr
  import numpy
  import pytest
  from onnx_chainer.testing import input_generator
  from onnx_chainer_tests.helper import ONNXModelTest
label_desc: Use image node_id 4 for calling the TestBinaryMathOperators obj's underlying member method code with example usage: obj.vector() and returns: a,  b