def __init__(self, func, string, step_type=None):
        super(RegexMatcher, self).__init__(func, string, step_type)
        assert not (string.startswith("^") or string.endswith("$")), \
            "Regular expression should not use begin/end-markers: "+ string
        expression = self.string % "^%s$"
        self.regex = re.compile(expression)
dataset/ETHPy150Open behave/behave/behave/matchers.py/RegexMatcher.__init__/swapped operands of `%`