interface Xtend { (target: T, source: U): T & U; (target: T, source1: U, source2: V): T & U & V; ( target: T, source1: U, source2: V, source3: W, ): T & U & V & W; ( target: T, source1: U, source2: V, source3: W, source4: Q, ): T & U & V & W & Q; ( target: T, source1: U, source2: V, source3: W, source4: Q, source5: R, ): T & U & V & W & Q & R; (target: object, ...sources: object[]): object; } declare const xtend: Xtend; export = xtend;