code: func Predicates(from Shape, in bool) Shape {
  	dir := quad.Subject
  	if in {
  		dir = quad.Object
  	}
  	return Unique{NodesFrom{
  		Quads: Quads{
  			{Dir: dir, Values: from},
  		},
  		Dir: quad.Predicate,
  	}}
  }
docs: // InWithTags, OutWithTags, Both, BothWithTags