Function stepper 

pub fn stepper<V>(value: V) -> Stepper<V>
where
    V: Binding<f64>,

stepper(value): a numeric field with increment/decrement arrows. value is a Signal<f64>, a day-model Field, or any other two-way binding; a step click commits one unit through it (write_commit), so under an undo stack each click is one undoable step.