'MessageTracker(*towatch)
Create a message tracker to track a set of mesages.
Parameters
*towatch : tuple of Event, MessageTracker, Message instances.
This list of objects to track. This class can track the low-level
Events used by the Message class, other MessageTrackers or
actual Messages.'

def __init__(self, *towatch):

    self.events = set()
    self.peers = set()
    for obj in towatch:
        if isinstance(obj, Event):
            self.events.add(obj)
        elif isinstance(obj, MessageTracker):
            self.peers.add(obj)
        elif isinstance(obj, Frame):
            if (not obj.tracker):
                raise ValueError('Not    a    tracked    message')
            self.peers.add(obj.tracker)
        else:
            raise TypeError(('Require    Events    or    Message    Frames,    not    %s' % type(obj)))
