Document the return value of `select()`

[markstos]

Some examples of calling select() are shown, but there is no formal documentation of the object returned. Exactly what attributes and methods does it have? Is it always an array?

[markstos]

Also, the return value when nothing is matches should be documented. Does it return an empty string? null? undefined? throw an error? Their is a lack of docs or examples for this case.

[markstos]

I checked that there are currently also no tests for a failed match, either.