code: def _npx_nonzero(a):
      """
      Return the indices of the elements that are non-zero.
  
      Returns a ndarray with ndim is 2. Each row contains the indices
      of the non-zero elements. The values in `a` are always tested and returned in
      row-major, C-style order.
  
      The result of this is always a 2-D array, with a row for
      each non-zero element.
  
      Parameters
      ----------
      a : array_like
          Input array.
  
      Returns
      -------
      array : ndarray
          Indices of elements that are non-zero.
  
      Notes
      -----
      This function differs from the original numpy.nonzero in the following aspects:
          - Does not support python numeric.
          - The return value is same as numpy.transpose(numpy.nonzero(a)).
  
      Examples
      --------
      >>> x = np.array([[3, 0, 0], [0, 4, 0], [5, 6, 0]])
      >>> x
      array([[3, 0, 0],
             [0, 4, 0],
             [5, 6, 0]])
      >>> npx.nonzero(x)
      array([[0, 0],
             [1, 1],
             [2, 0],
             [2, 1]], dtype=int64)
  
      >>> np.transpose(npx.nonzero(x))
      array([[0, 1, 2, 2],
             [0, 1, 0, 1]], dtype=int64)
      """
      pass
  
file_path: mxnet/python/mxnet/_numpy_op_doc.py
label_desc: Use image node_id 2 for calling a global function with example usage: _npx_nonzero(a) without return types