// Deletes usr from tree at the given coords func deleteUsr(mNS, mEW float64, usr *user.U, tree quadtree.T) { v := quadtree.PointViewP(mNS, mEW) pred := func(_, _ float64, e interface{}) bool { oUsr := e.(*user.U) return usr.Equiv(oUsr) } tree.Del(v, pred) }