code: def test_nnz_axis(self, xp, sp):
      m = self.make(xp, sp, self.dtype)
      return m.nnz
  
imports: import pickle
  import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy.cuda import driver
  from cupy.cuda import runtime
  from cupyx.scipy import sparse
label_desc: Use image node_id 3 for calling the TestDiaMatrixScipyComparison obj's underlying member method code with example usage: obj.test_nnz_axis(xp, sp) and returns: m