code: def add_column(self, width):
          
          tblGrid = self._tbl.tblGrid
          gridCol = tblGrid.add_gridCol()
          gridCol.w = width
          for tr in self._tbl.tr_lst:
              tc = tr.add_tc()
              tc.width = width
          return _Column(gridCol, self)
docs: Return a |_Column| object of *width*, newly added rightmost to the
          table.