public void RemovebillRow(billRow row) {
     this.Rows.Remove(row);
 }
 public billRowChangeEvent(billRow row, global::System.Data.DataRowAction action) {
     this.eventRow = row;
     this.eventAction = action;
 }
 public void AddbillRow(billRow row) {
     this.Rows.Add(row);
 }