if (sequenceType != null) { buf.append(" as "); buf.append(sequenceType.toString()); }
	public String pprint() {		StringBuffer buf = new StringBuffer();		buf.append("let ");		buf.append(varName);		buf.append(" := ");		buf.append(inputSequence.pprint());		if (whereExpr != null)			buf.append(" where ").append(whereExpr.pprint());		buf.append(" return ");		buf.append(returnExpr.pprint());		return buf.toString();	}