us copi function function directli todo gener special param sourc sourc generaliz element param target target generaliz element copi generaliz element object sourc object target sourc generaliz element target generaliz element illeg argument except sourc sourc target target copi model element sourc target generaliz element target ge generaliz element target generaliz element sourc ge generaliz element sourc target ge set sourc ge target ge set leaf sourc ge leaf target ge set root sourc ge root 