Comment by BigJono

I don't get it. Why is this a library? Looking at the example it doesn't seem to actually do anything other than generate a new colour given an existing colour and a luminosity value. Which is probably about 5 lines that any dev should be able to write on their own.

Your API includes a way to overwrite that functionality, which makes no sense. The last example is basically this:

  import foo
  foo(a, b, c) // returns c(a, b)

When I could just do this:

  c(a, b)