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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 where_pivot(self, column, operator=None, value=None, boolean="and"):
 """ Set a where clause for a pivot table column. :param column: The column of the where clause, can also be a QueryBuilder instance for sub where :type column: str|Builder :param operator: The operator of the where clause :type operator: str :param value: The value of the where clause :type value: mixed :param boolean: The boolean of the where clause :type boolean: str :return: self :rtype: self """

        self._pivot_wheres.append([column, operator, value, boolean])

        return self._query.where(
            "%s.%s" % (self._table, column), operator, value, boolean
        )