With the *user* parameter you can change the cgroups sub-directories. 
By default it will use the current user, i.e you are *paul* the cgroups will be created/loaded at `/sys/fs/cgroup/cpu/paul/`, `/sys/fs/cgroup/memory/paul/`, etc.
But if you use the library as sudo or root, you can specify an other *user* for the groups sub-directories, for example *docker* and the cgroups will be created/loaded at `/sys/fs/cgroup/cpu/docker/`, `/sys/fs/cgroup/memory/docker/`, etc.