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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 attach(self, id, filename, url):
 """Add an attachmemt to record from url :param id: ID of record :param filename: File name of attachment :param url: Public url to download file from. """

        Attachment = self.client.model('ir.attachment')
        return Attachment.add_attachment_from_url(
            filename, url, '%s,%s' % (self.model_name, id)
        )