'When ``jitter`` is specified, the values will all be within +/-
``jitter``.'

@given(greater_than_zero(), st.floats(min_value=0.0, allow_infinity=False))
def test_jitter(self, step, jitter):

    jitter_values = backoff(step=step, jitter=jitter, maximum_step=None, timeout=None)
    non_jitter_values = backoff(step=step, jitter=None, maximum_step=None, timeout=None)
    some_values = islice(izip(jitter_values, non_jitter_values), 0, 10)
    for (x, y) in some_values:
        assume((float('inf') not in (x, y)))
        difference = abs((x - y))
        self.assertLessEqual(difference, (jitter * 2), 'x:    {!r},    y:    {!r}'.format(x, y))
