code: func NewColumnsWithAlias(tableName string, tableAlias string) Columns {
  	return Columns{
  		lock:       &sync.RWMutex{},
  		Cols:       map[string]*Column{},
  		TableName:  tableName,
  		TableAlias: tableAlias,
  	}
  }
docs: // NewColumnsWithAlias constructs a list of columns for a given table
  // name, using a given alias for the table.