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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 update(self):
 """persist the .fields using .fields_where"""

        self.default_val = 0
        #fields = self.fields
        #fields = self.orm_class.depart(self.fields, is_update=True)
        #self.set_fields(fields)
        return self.interface.update(
            self.schema,
            self.fields,
            self
        )