more flexible saving: optionally don't overwrite
more flexible saving: optionally don't overwrite

massmutual/pystruct,massmutual/pystruct,wattlebird/pystruct,amueller/pystruct,pystruct/pystruct,pystruct/pystruct,wattlebird/pystruct,d-mittal/pystruct,amueller/pystruct,d-mittal/pystruct