code: func NewExecutor(b executorpkg.Backend, p plugin.Backend, i executorpkg.ImageBackend, v executorpkg.VolumeBackend) exec.Executor {
  	return &executor{
  		backend:       b,
  		pluginBackend: p,
  		imageBackend:  i,
  		volumeBackend: v,
  		dependencies:  agent.NewDependencyManager(),
  	}
  }
docs: // NewExecutor returns an executor from the docker client.