code: def addCategory(self, categoryUri, weight):
          
          assert isinstance(weight, (float, int)), "weight value has to be a positive or negative integer"
          self.topicPage["categories"].append({"uri": categoryUri, "wgt": weight})
docs: add a relevant category to the topic page
          @param categoryUri: uri of the category to be added
          @param weight: importance of the provided category (typically in range 1 - 50)