def _check_default_rule(self):
        if not self.default_rule:
            raise RuntimeError("Can't call parse() on a Grammar that has no "
                               "default rule. Choose a specific rule instead, "
                               "like some_grammar['some_rule'].parse(...).")
Raise RuntimeError if there is no default rule defined.
dataset/ETHPy150Open erikrose/parsimonious/parsimonious/grammar.py/Grammar._check_default_rule