code: func (r *Registry) All(kind string) []mo.Entity {
  	r.m.Lock()
  	defer r.m.Unlock()
  
  	var entities []mo.Entity
  	for ref, val := range r.objects {
  		if kind == "" || ref.Type == kind {
  			if e, ok := val.(mo.Entity); ok {
  				entities = append(entities, e)
  			}
  		}
  	}
  
  	return entities
  }
docs: // All returns all entities of type specified by kind.
  // If kind is empty - all entities will be returned.