code: def _init_go2ntpresent(go_ntsets, go_all, gosubdag):
          
          go2ntpresent = {}
          ntobj = namedtuple('NtPresent', " ".join(nt.hdr for nt in go_ntsets))
          # Get present marks for GO sources
          for goid_all in go_all:
              present_true = [goid_all in nt.go_set for nt in go_ntsets]
              present_str = ['X' if tf else '.' for tf in present_true]
              go2ntpresent[goid_all] = ntobj._make(present_str)
          # Get present marks for all other GO ancestors
          goids_ancestors = set(gosubdag.go2obj).difference(go2ntpresent)
          assert not goids_ancestors.intersection(go_all)
          strmark = ['.' for _ in range(len(go_ntsets))]
          for goid in goids_ancestors:
              go2ntpresent[goid] = ntobj._make(strmark)
          return go2ntpresent
docs: Mark all GO IDs with an X if present in the user GO list.