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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 field(self):
 """ Returns the field name that this column will have inside the database. :return <str> """

        if not self.__field:
            default_field = inflection.underscore(self.__name)
            if isinstance(self, orb.ReferenceColumn):
                default_field += '_id'
            self.__field = default_field

        return self.__field or default_field