code: func (qs *QuadStore) AddQuad(q quad.Quad) (int64, bool) {
  	p, _ := qs.resolveQuad(q, true)
  	if id := qs.quads[p]; id != 0 {
  		return id, false
  	}
  	pr := &primitive{Quad: p}
  	id := qs.addPrimitive(pr)
  	qs.quads[p] = id
  	for _, t := range qs.indexesForQuad(p) {
  		t.Set(id, pr)
  	}
  	// TODO(barakmich): Add VIP indexing
  	return id, true
  }
docs: // AddQuad adds a quad to quad store. It returns an id of the quad.
  // False is returned as a second parameter if quad exists already.