def evaluate_script(self, script, **kwargs):
        """
        Evaluates the supplied script (python-executable string).
        Useful for testing your scripts!

        globals already include all of numpy objects plus

        self = self
        f    = self.f
        bg   = self.bg

        and all the current guess parameters and constants

        kwargs are added to globals for script evaluation.
        """
        self._set_data_globals.update(kwargs)
        return eval(script, self._set_data_globals)