bank account sample ported from IO language

// https://github.com/stevedekorte/io/blob/master/samples/misc/Account.io

start()->
    Account = #<obj>{
        balance = 0.0
        deposit = method(V)-> This.balance := This.balance + V
        show    = method()-> @"Account balance: $#{This.balance}\n"
    }

    io.format( @"Inital: #{Account.show()}") 

    io.format( "Depositing $10\n" )
    Account.deposit(10.0)

    io.format( @"Final: #{Account.show()}" )