FuncFrog: fast, parallel and lazy stream-api. Please help me with the code review and project development ideas

I have finally released a stable version of my stream-like library. It now supports some basic features such as Map, Reduce, Filter, on any slice or generating function, easy out-of-the-box parallelism with minimum locks and overhead on a regular for cycle.
Here it is: GitHub - koss-null/FuncFrog: Stream api (kind of) implementation for go, other useful functions and packages to use go in a functional way
First of all I will appreciate any code review. Any feedback is welcome.
At second, I want to ask the community, what features do you expect to be in such kind of a library and how do you expect them to be implemented? It looks like I need to add some Collect function to be able to produce not only slices, and also add some sources such as BufferedReader or channel.

here is some performance comparison of this kind of libraries