def write_external_book_rel(book):
 root = Element('Relationships', xmlns=PKG_REL_NS)
 rel = Relationship('', target=book.Target, targetMode=book.TargetMode, id='rId1')
 rel.type = book.Type
 root.append(rel.to_tree())
 return root

def write_external_book_rel ( book ) : root = Element ( 'Relationships' , xmlns = PKG_REL_NS ) rel = Relationship ( '' , target = book . Target , targetMode = book . TargetMode , id = 'rId1' ) rel . type = book . Type root . append ( rel . to_tree ( ) ) return root
serialise link to external file .