Validating a component callback

[bmakan]

I am doing a research on ts types and prop-types and this library seems to be the best solution I've come across so far. But, unless I'm missing something, there is no a built-in way to validate callbacks (or there won't be one in the future). t.Function is deprecated and will be removed eventually.
Should some kind of FunctionType be added to the library to cover this use-case?