Check if any of exception classes caused the failure/s.

        :param exc_classes: exception types/exception type names to
                            search for.

        If any of the contained failures were caused by an exception of a
        given type, the corresponding argument that matched is returned. If
        not then ``None`` is returned.

def check(self, *exc_classes):
        """Check if any of exception classes caused the failure/s.

        :param exc_classes: exception types/exception type names to
                            search for.

        If any of the contained failures were caused by an exception of a
        given type, the corresponding argument that matched is returned. If
        not then ``None`` is returned.
        """
        if not exc_classes:
            return None
        for cause in self:
            result = cause.check(*exc_classes)
            if result is not None:
                return result
        return None