code: func NewHistory(author, comment, createdBy string, isEmptyLayer bool) History {
  	return History{
  		Author:     author,
  		Created:    time.Now().UTC(),
  		CreatedBy:  createdBy,
  		Comment:    comment,
  		EmptyLayer: isEmptyLayer,
  	}
  }
docs: // NewHistory creates a new history struct from arguments, and sets the created
  // time to the current time in UTC