code: func (t *TableMap) SetUniqueTogether(fieldNames ...string) *TableMap {
  	if len(fieldNames) < 2 {
  		panic(fmt.Sprintf(
  			"gorp: SetUniqueTogether: must provide at least two fieldNames to set uniqueness constraint."))
  	}
  
  	columns := make([]string, 0, len(fieldNames))
  	for _, name := range fieldNames {
  		columns = append(columns, name)
  	}
  
  	for _, existingColumns := range t.uniqueTogether {
  		if equal(existingColumns, columns) {
  			return t
  		}
  	}
  	t.uniqueTogether = append(t.uniqueTogether, columns)
  	t.ResetSql()
  
  	return t
  }
docs: // SetUniqueTogether lets you specify uniqueness constraints across multiple
  // columns on the table. Each call adds an additional constraint for the
  // specified columns.
  //
  // Automatically calls ResetSql() to ensure SQL statements are regenerated.
  //
  // Panics if fieldNames length < 2.
  //