code: def testSparseSum(self):
      x = jnp.arange(20).reshape(4, 5)
      xsp = BCOO.fromdense(x)
  
      def f(x):
          return x.sum(), x.sum(0), x.sum(1), x.sum((0, 1))
  
      result_dense = f(x)
      result_sparse = self.sparsify(f)(xsp)
  
      assert len(result_dense) == len(result_sparse)
  
      for res_dense, res_sparse in zip(result_dense, result_sparse):
          if isinstance(res_sparse, BCOO):
              res_sparse = res_sparse.todense()
          self.assertArraysAllClose(res_dense, res_sparse)
  
imports: from functools import partial
  import math
  import operator
  from absl.testing import absltest
  from absl.testing import parameterized
  import numpy
  import jax
  from jax import config, jit, lax
  import jax.numpy
  import jax._src.test_util
  from jax.experimental.sparse import BCOO, BCSR, sparsify, todense, SparseTracer
  from jax.experimental.sparse.transform import arrays_to_spvalues, spvalues_to_arrays, sparsify_raw, SparsifyValue, SparsifyEnv
  from jax.experimental.sparse.util import CuSparseEfficiencyWarning
  from jax.experimental.sparse import test_util
label_desc: Use image node_id 16 for calling the SparsifyTest obj's underlying member method code with example usage: obj.testSparseSum() and returns: x,  x,  x,  x