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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def connect(receiver, signal=Any, sender=Any, weak=True):
 """Connect receiver to sender for signal receiver -- a callable Python object which is to receive messages/signals/events. Receivers must be hashable objects. if weak is True, then receiver must be weak-referencable (more precisely saferef.safeRef() must be able to create a reference to the receiver). Receivers are fairly flexible in their specification, as the machinery in the robustApply module takes care of most of the details regarding figuring out appropriate subsets of the sent arguments to apply to a given receiver. Note: if receiver is itself a weak reference (a callable), it will be de-referenced by the system's machinery, so *generally* weak references are not suitable as receivers, though some use might be found for the facility whereby a higher-level library passes in pre-weakrefed receiver references. signal -- the signal to which the receiver should respond if Any, receiver will receive any signal from the indicated sender (which might also be Any, but is not necessarily Any). Otherwise must be a hashable Python object other than None (DispatcherError raised on None). sender -- the sender to which the receiver should respond if Any, receiver will receive the indicated signals from any sender. if Anonymous, receiver will only receive indicated signals from send/sendExact which do not specify a sender, or specify Anonymous explicitly as the sender. Otherwise can be any python object. weak -- whether to use weak references to the receiver By default, the module will attempt to use weak references to the receiver objects. If this parameter is false, then strong references will be used. returns None, may raise DispatcherTypeError """

    if signal is None:
        raise errors.DispatcherTypeError(
            'Signal cannot be None (receiver=%r sender=%r)'%( receiver,sender)
        )
    if weak:
        receiver = saferef.safeRef(receiver, onDelete=_removeReceiver)
    senderkey = id(sender)
    if senderkey in connections:
        signals = connections[senderkey]
    else:
        connections[senderkey] = signals = {}
    # Keep track of senders for cleanup.
    # Is Anonymous something we want to clean up?
    if sender not in (None, Anonymous, Any):
        def remove(object, senderkey=senderkey):
            _removeSender(senderkey=senderkey)
        # Skip objects that can not be weakly referenced, which means
        # they won't be automatically cleaned up, but that's too bad.
        try:
            weakSender = weakref.ref(sender, remove)
            senders[senderkey] = weakSender
        except:
            pass
        
    receiverID = id(receiver)
    # get current set, remove any current references to
    # this receiver in the set, including back-references
    if signal in signals:
        receivers = signals[signal]
        _removeOldBackRefs(senderkey, signal, receiver, receivers)
    else:
        receivers = signals[signal] = []
    try:
        current = sendersBack.get( receiverID )
        if current is None:
            sendersBack[ receiverID ] = current = []
        if senderkey not in current:
            current.append(senderkey)
    except:
        pass

    receivers.append(receiver)