<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_worksheet(self):
 """Add a worksheet to the workbook."""

        wsh = self.workbook.add_worksheet()
        if self.vars.fld2col_widths is not None:
            self.set_xlsx_colwidths(wsh, self.vars.fld2col_widths, self.wbfmtobj.get_prt_flds())
        return wsh