human
Complete the below
@pytest.fixture(scope='module', params=['cpu'])
def backend_cpu64(request):

    ''''Fixture that returns a cpu backend using 64 bit dtype.
    For use in tests like gradient checking which need higher
    precision'
    '''

Give me a the Python code you requested?
assistant
#Here is the Python code you requested.
    be = get_backend(request, datatype=np.float64)
    def cleanup():
        be = request.getfixturevalue('backend_cpu64')
        del be
    request.addfinalizer(cleanup)
    return be