import uuid

LEFT_MOUSE = 1
MIDDLE_MOUSE = 2
RIGHT_MOUSE = 3
WHEEL_UP = 4
WHEEL_DOWN = 5

callbacks = {}

class Object(object):
    def __init__(self):
        self._id = uuid.uuid4()

    def id(self):
        return self._id

def register(obj, button=None, cmd=None):
    callbacks.setdefault(obj.id(), {}).setdefault(button, []).append(cmd)

def trigger(event):
    for field in ['instance', 'name']:
        if field in event:
            cb = callbacks.get(event[field])
            _invoke(event, cb)

def _invoke(event, callback):
    if not callback: return
    if not 'button' in event: return

    for cb in callback.get(event['button']):
        if callable(cb):
            cb(event)

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