code: def get_usrgo2hdrgo(self):
          
          usrgo2hdrgo = {}
          for hdrgo, usrgos in self.hdrgo2usrgos.items():
              for usrgo in usrgos:
                  assert usrgo not in usrgo2hdrgo
                  usrgo2hdrgo[usrgo] = hdrgo
          # Add usrgos which are also a hdrgo and the GO group contains no other GO IDs
          for goid in self.hdrgo_is_usrgo:
              usrgo2hdrgo[goid] = goid
          assert len(self.usrgos) <= len(usrgo2hdrgo), \
              "USRGOS({U}) != USRGO2HDRGO({H}): {GOs}".format(
                  U=len(self.usrgos),
                  H=len(usrgo2hdrgo),
                  GOs=self.usrgos.symmetric_difference(set(usrgo2hdrgo.keys())))
          return usrgo2hdrgo
docs: Return a dict with all user GO IDs as keys and their respective header GOs as values.