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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 marker(self):
 """ The |Marker| instance for this point, providing access to the visual properties of the data point marker, such as fill and line. Setting these properties overrides any value set at the series level. """

        dPt = self._ser.get_or_add_dPt_for_point(self._idx)
        return Marker(dPt)