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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 addRelationship(self, originItemId, destinationItemId, relationshipType):
 """ Adds a relationship of a certain type between two items. Inputs: originItemId - The item ID of the origin item of the relationship destinationItemId - The item ID of the destination item of the relationship. relationshipType - The type of relationship between the two items. Must be defined in Relationship types. """

        url = "%s/addRelationship" % self.root
        params = {
            "originItemId" : originItemId,
            "destinationItemId": destinationItemId,
            "relationshipType" : relationshipType,
            "f" : "json"
        }
        return self._post(url=url,
                             param_dict=params,
                             securityHandler=self._securityHandler,
                             proxy_port=self._proxy_port,
                             proxy_url=self._proxy_url)