fn divide(state: &mut State) {
    let a = state.stack.pop();
    let b = state.stack.pop();
    state.stack.push(b / a);
}
// divide performs b / a => does NOT user prompt
divide performs b / a => does NOT user prompt
divide performs b / a = > does NOT user prompt
fn divide(state: &mut State) {
    let a = state.stack.pop();
    let b = state.stack.pop();
    state.stack.push(b / a);
}
fn divide ( state : & mut State ) { let a = state . stack . pop ( ) ; let b = state . stack . pop ( ) ; state . stack . push ( b / a ) ; }
divide performs b / a => does NOT user prompt
divide performs b / a = > does NOT user prompt
state
&mut State
state
&mut State