Explain what this library does in the README.md

[jasondavis]

Explain what this library does in the README.md.

Looking at the examples, it shows the same output for every demo so I am trying to figure out just what this library does. Can someone explain a little better please and thank you?

It says:

The idea is to allow the callback to decide at runtime whether the loop will be synchronous or asynchronous. By using this in a creative way (in situations where that value isn't already spoken for), an entire control API can be offered without over-complicating function signatures.

So what does this mean exactly? As in what is the actual visual difference of the 2?

the loop will be synchronous or asynchronous