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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 addSource(self, sourceUri, weight):
 """ add a news source to the topic page @param sourceUri: uri of the news source to add to the topic page @param weight: importance of the news source (typically in range 1 - 50) """

        assert isinstance(weight, (float, int)), "weight value has to be a positive or negative integer"
        self.topicPage["sources"].append({"uri": sourceUri, "wgt": weight})