use metaclass directly (#2952)
use metaclass directly (#2952)


spotify/luigi,spotify/luigi,jamesmcm/luigi,riga/luigi,riga/luigi,spotify/luigi,dlstadther/luigi,riga/luigi,jamesmcm/luigi,dlstadther/luigi,spotify/luigi,dlstadther/luigi,jamesmcm/luigi,riga/luigi,dlstadther/luigi,jamesmcm/luigi