Exercise - https://github.com/gophercises/urlshort.

JSONHandler will parse the provided JSON and then return a http.HandlerFunc (which also implements http.Handler) that will attempt to map any paths to their corresponding URL.

MapHandler will return a http.HandlerFunc (which also implements http.Handler) that will attempt to map any paths (keys in the map) to their corresponding URL (values that each key in the map points to, in string format).