'Adds a breakpoint which would trigger on `event_type`.
:param event_type:  The event type to trigger on
:param bp:          The breakpoint
:return:            The created breakpoint.'

def add_breakpoint(self, event_type, bp):

    if (event_type not in event_types):
        raise ValueError(('Invalid    event    type    %s    passed    in.    Should    be    one    of:    %s' % (event_type, ',    '.join(event_types))))
    self._breakpoints[event_type].append(bp)
