static Web webFromTriple(S a, S b, S c) {
  ret webFromTriple(triple(a, b, c));
}

static Web webFromTriple(Triple<S> t) {
  ret webFromTriple(t, 0.2, 0.2, 0.8, 0.7);
}

static Web webFromTriple(Triple<S> t, double x1, double y1, double x2, double y2) {
  Web web = webWithoutIndexAndLock(); // save space
  S a = unnull(t.a), b = unnull(t.b), c = unnull(t.c);
  web_addRelation(web, a, c, b);
  //Web web = webFromTriples(t.a, t.b, t.c);
  
  web_setPosition(first(web.nodes), x1, y1);
  web_setPosition(second(web.nodes), x2, y2);
  
  if (t instanceof TripleWeb) {
    TripleWeb w = cast t;
    web.globalID = w.globalID;
    web.created = w.created;
    web.source = w.source;
  }
  
  ret web;
}