How to use the pykeepass.attachment.Attachment function in pykeepass

def add_attachment(self, id, filename):
        element = E.Binary(
            E.Key(filename),
            E.Value(Ref=str(id))
        )
        self._element.append(element)

        return pykeepass.attachment.Attachment(element=element, kp=self._kp)

tree = self.tree
        logger.debug(xpath_str)
        elements = tree.xpath(
            xpath_str, namespaces={'re': 'http://exslt.org/regular-expressions'}
        )

        res = []
        for e in elements:
            if history or e.getparent().tag != 'History':
                if cast:
                    if e.tag == 'Entry':
                        res.append(Entry(element=e, kp=self))
                    elif e.tag == 'Group':
                        res.append(Group(element=e, kp=self))
                    elif e.tag == 'Binary' and e.getparent().tag == 'Entry':
                        res.append(Attachment(element=e, kp=self))
                    else:
                        raise Exception('Could not cast element {}'.format(e))
                else:
                    res.append(e)

        # return first object in list or None
        if first:
            res = res[0] if res else None

        return res