'Extend our messages with another message or set of messages.
@param other: The messages to include.
@type other: L{MessageSet}, L{tuple} of two L{int}s, or a
single L{int}'

def extend(self, other):

    if isinstance(other, MessageSet):
        self.ranges.extend(other.ranges)
        self.clean()
    else:
        try:
            self.add(*other)
        except TypeError:
            self.add(other)
    return self
