Make input and output generic/minimize code duplication

[BlackPhlox]

Something like this can also be implemented for input, maybe we can do something more generic for both of them?

Originally posted by @BlackPhlox in #12 (comment)

[grace125]

I'm starting to think that while input/output should be more similar, it wouldn't make sense to make the APIs actually generic. There won't be much code duplication in the changes I'm going to propose.

[BlackPhlox]

Yeah, generic was the wrong word here. End goal is to minimize code duplication, not be made generic.

[grace125]

Ah okay good, glad we're on the same page!