Add String Formatting to widgets

[MaxKasper]

Problem

I use the IntRangeSlider widget to limit an axis in an interactive plot. I wish I had an attribute to define a Stringformatter like in Matplotlib, so I can display the ranges for example as time intervalls.

Proposed Solution

Add an attribute to the widget, to apply string forattimg options. Option to apply functions like datetime.strftime() or

Additional context

Matplotlib offers "matplotlib.ticker.FuncFormatter" which is quite similar.