def validate(self, value):
        super(Regex, self).validate(value)

        if not (value is None or self.regex.match(value) is not None):
            raise ValueError((self.regex.pattern, value) % "expected a string matching %r pattern, got %r")
dataset/ETHPy150Open bokeh/bokeh/bokeh/core/properties.py/Regex.validate/swapped operands of `%`