code: def test_sum(self, xp, dtype):
      return lambda x: x.sum()
  
imports: import unittest
  import numpy
  from cupy import testing
  from cupy_tests.core_tests.fusion_tests import fusion_utils
label_desc: Use image node_id 3 for calling the TestFusionArrayMethods obj's underlying member method code with example usage: obj.test_sum(xp, dtype) and returns: function