private void sortExprs(final List list) {
			Collections.sort(list, new Comparator() {
				public int compare(final Object a, final Object b) {
					if (a == b) {
						return 0;
					}

					final int ka = ((Expr) a).key();
					final int kb = ((Expr) b).key();

					return ka - kb;
				}
			});
		}