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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def openSheet(self, name):
        ''' set a sheet to write '''
        if name not in self.__sheetNameDict:
            sheet = self.__workbook.add_sheet(name)
            self.__sheetNameDict[name] = sheet

        self.__sheet = self.__sheetNameDict[name]