class_docstr: This is purely for onenormest testing.
class_docstr_tok: ["This","is","purely","for","onenormest","testing","."]
code: def _matvec(self, x):
      return np.dot(self.A, np.dot(self.B, x))
  
imports: from __future__ import division, print_function, absolute_import
  import numpy
  from numpy.testing import assert_allclose, assert_equal, assert_
  import pytest
  import scipy.linalg
  import scipy.sparse.linalg
  from scipy.sparse.linalg._onenormest import _onenormest_core, _algorithm_2_2
label_desc: Use image node_id 2 for calling the MatrixProductOperator obj's underlying member method code with example usage: obj._matvec(x) and returns: np