code: func (b *Branch) Validate() error {
  	if b.Name == "" {
  		return errBranchEmptyName
  	}
  
  	if b.Merge != "" && !b.Merge.IsBranch() {
  		return errBranchInvalidMerge
  	}
  
  	return nil
  }
docs: // Validate validates fields of branch