Use modularity / up to Exercise 1-12
drwxr-xr-x - dup
drwxr-xr-x - echo
drwxr-xr-x - fetch
drwxr-xr-x - fetchall
-rw-r--r-- 46 go.mod
drwxr-xr-x - httpserve
drwxr-xr-x - lissajous
-rw-r--r-- 106 main.go