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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 distinct_on(self, value):
 """Set fields used to group query results. :type value: str or sequence of strings :param value: Each value is a string giving the name of a property to use to group results together. """

        if isinstance(value, str):
            value = [value]
        self._distinct_on[:] = value