public boolean enter(String s, SymtabEntry e) {
		boolean isNew = true;
		SymtabEntry value = lookup(s);
		if (value != null)
			if (value.getScope().equals(e.getScope()))
				isNew = false;
		m.put(s, e);
		if (isNew)
			l.add(s);
		return isNew;
	}