code: public static StringBuilder appendCalcArgs(StringBuilder sb, CalcArgs args) {
  	    final String astr = args.evaluate(CalcArgs.stringEvaluator);
  	    if (!astr.startsWith(FUNCTION_OPENING)) {
  	        sb.append(FUNCTION_OPENING);
  	        sb.append(astr);
  	        sb.append(FUNCTION_CLOSING);
  	    } else {
  	        sb.append(astr);
  	    }
  	    return sb;
  	}
docs: Appends the calc() function arguments to a string builder.
  @param sb the string builder to be modified
  @param args the calc arguments
  @return Modified <code>sb</code> to allow chaining