public bool VerifyAssignement(SimpleAssignement assign, Environment env)
        {
            type t1 = env.GetType(assign.name);
            type t2 = GetType(assign.tree, env);

            return(AssignementMatches(t1, t2));
        }
 public String Print(SimpleAssignement sassign)
 {
     return(sassign.name + "=" + Print(sassign.tree));
 }