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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 setDocumentedBy(self, documented_pid, documenting_pid):
 """Add a CiTO, the Citation Typing Ontology, triple asserting that ``documented_pid`` isDocumentedBy ``documenting_pid``. Adds assertion: ``documented_pid cito:isDocumentedBy documenting_pid`` Args: documented_pid: str PID of a Science Object that is documented by ``documenting_pid``. documenting_pid: str PID of a Science Object that documents ``documented_pid``. """

        self._check_initialized()
        documented_id = self.getObjectByPid(documented_pid)
        documenting_id = self.getObjectByPid(documenting_pid)
        self.add((documented_id, CITO.isDocumentedBy, documenting_id))