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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 add_delegate(self, callback):
 """ Registers a new delegate callback The prototype should be function(data), where data will be the decoded json push Args: callback (function):
 method to trigger when push center receives events """


        if callback in self._delegate_methods:
            return

        self._delegate_methods.append(callback)