code: func newEntity(index, serial int32, class *class) *Entity {
  	return &Entity{
  		index:   index,
  		serial:  serial,
  		class:   class,
  		active:  true,
  		state:   newFieldState(),
  		fpCache: make(map[string]*fieldPath),
  		fpNoop:  make(map[string]bool),
  	}
  }
docs: // newEntity returns a new entity for the given index, serial and class