Returns the first cell after the last child in a traversal of children a given level deeper than this cell, in Hilbert curve order. The given level must be no smaller than the cell's level. The returned cell may be invalid.
Returns the first cell after the last child in a traversal of children a given level deeper than this cell, in Hilbert curve order. The given level must be no smaller than the cell's level. The returned cell may be invalid.