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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 onex(self):
 """ delete all X columns except the first one. """

        xCols=[i for i in range(self.nCols) if self.colTypes[i]==3]
        if len(xCols)>1:
            for colI in xCols[1:][::-1]:
                self.colDelete(colI)