package symbols;import java.util.*; import lexer.*; import inter.*;public class Env {	private Hashtable table;	protected Env prev;	public Env(Env n) { table = new Hashtable(); prev = n; }	public void put(Token w, Id i) { table.put(w, i); }	public Id get(Token w) {		for( Env e = this; e != null; e = e.prev ) {			Id found = (Id)(e.table.get(w));			if( found != null ) return found;		}		return null;	}}