open.account=function(d.amount, w.amount){
     list(
     deposit=function(d.amount){
     if(d.amount<0)
     stop('Deposits must be positive!\n')
     total<<-total+d.amount
     cat(d.amount,"deposited. Your balance is",total,"\n\n")
     },
     withdraw=function(w.amount){
     if(w.amount>total)
     stop("You don't have that much money!\n")
     total<<-total-w.amount
     cat(w.amount,"withdraw. Your balance is",total,"\n\n")

     },
     balance=function(){
     cat("Your balance is",total,"\n\n")
     total}
       )
    }


total=100
ross=open.account(0,0)  
ross$balance()   
ross$deposit(20)   

ross$withdraw(30)