docs: def bottom(self):
          """
          The row index that marks the bottom extent of the vertical span of
          this cell. This is one greater than the index of the bottom-most row
          of the span, similar to how a slice of the cell's rows would be
          specified.
          """
          if self.vMerge is not None:
              tc_below = self._tc_below
              if tc_below is not None and tc_below.vMerge == ST_Merge.CONTINUE:
                  return tc_below.bottom
          return self._tr_idx + 1