code: func (l *libcontainerAdapter) newManager(cgroups *libcontainerconfigs.Cgroup, paths map[string]string) (libcontainercgroups.Manager, error) {
  	switch l.cgroupManagerType {
  	case libcontainerCgroupfs:
  		return &cgroupfs.Manager{
  			Cgroups: cgroups,
  			Paths:   paths,
  		}, nil
  	case libcontainerSystemd:
  		// this means you asked systemd to manage cgroups, but systemd was not on the host, so all you can do is panic...
  		if !cgroupsystemd.UseSystemd() {
  			panic("systemd cgroup manager not available")
  		}
  		return &cgroupsystemd.Manager{
  			Cgroups: cgroups,
  			Paths:   paths,
  		}, nil
  	}
  	return nil, fmt.Errorf("invalid cgroup manager configuration")
  }
docs: // newManager returns an implementation of cgroups.Manager