Mark all GO IDs with an X if present in the user GO list.

def _init_go2ntpresent(go_ntsets, go_all, gosubdag):
        """Mark all GO IDs with an X if present in the user GO list."""
        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