add on function overloading for better type hints

[liqiuqiui]

Description

Add type overloading to the on and off function to obtain better type hints in development. An example is shown in the following figure:

Checklist

• Created tests which fail without the change (if possible)
• All tests passing (yarn test)
• Extended the README / documentation, if necessary

[adumesny]

thnaks, this handles the string case as well (might need to make an array option as well).