internal ValuesNextEnumerator(MultiValueCursor cursor, DbCursorOp opNext)
 {
     this.cursor    = cursor;
     this.opNext    = opNext;
     this.current   = default;
     this.isCurrent = false;
 }
 internal ValuesEnumerator(MultiValueCursor cursor, DbCursorOp opFirst, DbCursorOp opNext)
 {
     this.cursor        = cursor;
     this.opFirst       = opFirst;
     this.opNext        = opNext;
     this.current       = default(ReadOnlySpan <byte>);
     this.isCurrent     = false;
     this.isInitialized = false;
 }
 internal ValuesNextIterator(MultiValueCursor cursor, DbCursorOp opNext)
 {
     this.cursor = cursor;
     this.opNext = opNext;
 }