docstr: Returns the number of stored values, including explicit zeros.
  
  Args:
      axis: Not supported yet.
  
  Returns:
      int: The number of stored values.
code: def getnnz(self, axis=None):
      """Returns the number of stored values, including explicit zeros.
  
      Args:
          axis: Not supported yet.
  
      Returns:
          int: The number of stored values.
  
      """
      if axis is None:
          return self.data.size
      else:
          raise ValueError
  
imports: import string
  import warnings
  import numpy
  import cupy
  import cupyx
  from cupy import _core
  from cupy._core import _scalar
  from cupy._creation import basic
  from cupyx.scipy.sparse import _base
  from cupyx.scipy.sparse import _coo
  from cupyx.scipy.sparse import _data
  from cupyx.scipy.sparse import _sputils
  from cupyx.scipy.sparse import _util
  from cupyx.scipy.sparse import _index
label_desc: Use image node_id 32 for calling the _compressed_sparse_matrix obj's underlying member method code with example usage: obj.getnnz(axis) and returns: self