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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 delete(self):
 """Delete a file instance. The file instance can be deleted if it has no references from other objects. The caller is responsible to test if the file instance is writable and that the disk file can actually be removed. .. note:: Normally you should use the Celery task to delete a file instance, as this method will not remove the file on disk. """

        self.query.filter_by(id=self.id).delete()
        return self