A beverage container containing a removable lid, the container comprising a rim, a side wall depending from the rim, a shoulder portion extending inwardly from the side wall, the removable lid comprising an edge extending over the rim, and along the side wall, and against the shoulder portion thereby attaching the lid to the container. Subsequently, a threshold voltage of a program disturbance is measured in accordance with change of the pass voltage applied to the cell not selected under the condition that a program voltage having a certain level is provided to a cell selected of the erased cells. Stable and efficient doping can be achieved. The main end risers 42 of the main structure provide ports on one distal end to allow the user to attach other units, via main couplers 40, to expand the apparatus to a larger size.