def subscribe(receiver):
    """Register an IStatusReceiver to receive new status events. The
        receiver will immediately be sent a set of 'builderAdded' messages
        for all current builders. It will receive further 'builderAdded' and
        'builderRemoved' messages as the config file is reloaded and builders
        come and go. It will also receive 'buildsetSubmitted' messages for
        all outstanding BuildSets (and each new BuildSet that gets
        submitted). No additional messages will be sent unless the receiver
        asks for them by calling .subscribe on the IBuilderStatus objects
        which accompany the addedBuilder message."""
