code: func NewAggregate(errs ...error) error {
  	// filter out possible nil values
  	var nonNils []error
  	for _, err := range errs {
  		if err != nil {
  			nonNils = append(nonNils, err)
  		}
  	}
  	if len(nonNils) == 0 {
  		return nil
  	}
  	return wrapWithDepth(aggregate(nonNils), 2)
  }
docs: // NewAggregate creates a new aggregate instance from the specified
  // list of errors