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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 _get_sender(*sender_params, **kwargs):
 """ Utility function acting as a Sender factory - ensures senders don't get created twice of more for the same target server """

    notify_func = kwargs['notify_func']
    with _sender_instances_lock:
        existing_sender = _sender_instances.get(sender_params, None)
        if existing_sender:
            sender = existing_sender
            sender._notify = notify_func
        else:
            sender = _Sender(*sender_params, notify=notify_func)
        _sender_instances[sender_params] = sender
        return sender