## strlenprog

### Instructions

- Write a program that counts the characters of a `string` and that returns that value.

- If the program receives more than one `string` or no arguments must not return anything (see the `Expected output`).

### Expected output :

```console
student@ubuntu:~/piscine-go/strlenprog$ go build
student@ubuntu:~/piscine-go/strlenprog$ ./strlenprog "hello"
5
student@ubuntu:~/piscine-go/strlenprog$ ./strlenprog
student@ubuntu:~/piscine-go/strlenprog$
student@ubuntu:~/piscine-go/strlenprog$ ./strlenprog "hello" "how are you"
student@ubuntu:~/piscine-go/strlenprog$
```