question: public String explain ( ) { StringBuffer sb = new StringBuffer ( ) ; sb . append ( "I don't understand your formula " ) ; quotify ( sb , scanner . getInput ( ) ) ; sb . append ( ".\n\n" ) ; explainWhere ( sb ) ; explainWhy ( sb ) ; explainWhat ( sb ) ; return sb . toString ( ) ; }
target:  Give a long, hopefully helpful error message.