Every cell in an Excel workbook contains a unique cell style. This style is exposed by ExcelWriter through the CellStyle class. Changes to a
CellStyle affect only the cell that owns the style. A
CellStyle may be "set" on another cell or group of cells, but this action clones the style. Changes to the original
CellStyle reference affect only the owning cell and changes to the cloned
CellStyle affect only the cell on which the style was set. If the style is "set" on a cell grouping object, such as an area, range, row, or column, each cell in the grouping receives a unique clone of the style.