Return a boolean if the choice is a number in the enumeration

def validate(self, value):
        """Return a boolean if the choice is a number in the enumeration"""
        if value in list(self.choices.keys()):
            self._choice = value
            return True
        try:
            self._choice = list(self.choices.keys())[int(value)]
            return True
        except (ValueError, IndexError):
            self.error_message = '%s is not a valid choice.' % value
            return False