Adds a global check to the bot.

        This is the non-decorator interface to :meth:`.check`
        and :meth:`.check_once`.

        Parameters
        -----------
        func
            The function that was used as a global check.
        call_once: :class:`bool`
            If the function should only be called once per
            :meth:`.Command.invoke` call.

def add_check(self, func, *, call_once=False):
        """Adds a global check to the bot.

        This is the non-decorator interface to :meth:`.check`
        and :meth:`.check_once`.

        Parameters
        -----------
        func
            The function that was used as a global check.
        call_once: :class:`bool`
            If the function should only be called once per
            :meth:`.Command.invoke` call.
        """

        if call_once:
            self._check_once.append(func)
        else:
            self._checks.append(func)