You can just expose two different functions, one of which takes a byte slice and one of which takes an io.Reader. Given how the code works (it starts by buffer

You can just expose two different functions, one of which takes a byte slice and one of which takes an io.Reader. Given how the code works (it starts by buffering the input stream), the second function will just be a few lines of code followed by a call to the first. Perfect example of how complex type systems can lead people to have unnecessarily complex thoughts.