> This is actually quite straightforward after being referred as the vector method call (basically map) and the other stuff is just function/operator calls apar

> This is actually quite straightforward after being referred as the vector method call (basically map) and the other stuff is just function/operator calls apart from maybe the :by{.chars} which I can assume what it's doing but only after seeing the implementation I can see that it's something like a named parameter with a lambda This doesn't remotely explain what that line of code is doing.