Let us write the URL shortening service to explain all the concepts we discussed in the preceding section. Before that, let us design a package that implements the Base62 algorithm with encoding/decoding functions. The URL shortening technique needs the Base62 algorithm to convert a long URL to short, and vice versa. We then write a solid example to show how this encoding works. Create a directory called base62 in the GOPATH:

mkdir $GOPATH/src/github.com/narenaryan/base62

Now, add a file called encodeutils.go, which houses our encode and decode functions.