The purpose of the following function is to help balance a checkbook. The function prompts the user for an initial balance. Then it enters the loop in which it requests a number from the user, subtracts it from the current balance, and keeps track of the new balance. Deposits are entered by inputting a negative number. It passes the first obj as the first parameter to procedure, the second obj as the second and so on.
List is the remag arguments into a list to procedure.
This is useful when some or all of the arguments are in a list. Display is mainly for printing messages that do not have to show the type of object that is being printed. Thus, it is better for standard output. An error is displayed if the file cannot be opened. References Abelson, Harold.