code: func filterContainer(c *pb.Container, filter *pb.ContainerFilter) bool {
  	if filter != nil {
  		if filter.State != nil {
  			if c.State != filter.State.State {
  				return false
  			}
  		}
  		if filter.LabelSelector != nil {
  			sel := fields.SelectorFromSet(filter.LabelSelector)
  			if !sel.Matches(fields.Set(c.Labels)) {
  				return false
  			}
  		}
  	}
  	return true
  }
docs: // filterContainer returns whether passed container matches filtering criteria