code: public Attribute getAttribute4Select(final String _selectStmt)
      {
          final OneSelect oneselect = this.selectStmt2OneSelect.get(_selectStmt);
          return oneselect == null ? null : oneselect.getAttribute();
      }
docs: Method to get the Attribute used for an select.
  
  @param _selectStmt selectstatement the attribute is wanted for
  @return Attribute for the selectstatement