require(toLocked.end >= fromLocked.end, "Only delegate to longer lock");
    function testSuccessDelegate() public {
        // successful delegate
        testSuccessCreateLock();
        vm.warp(8 days); // warp more than 1 week so both users are not locking in same epoch
        vm.prank(user2);
        ve.createLock{value: LOCK_AMT}(LOCK_AMT);
        vm.prank(user1);
        ve.delegate(user2);
        (, , , address delegatee) = ve.locked(user1);
        assertEq(delegatee, user2);
        (, , int128 delegated, ) = ve.locked(user2);
        assertEq(delegated, 2000000000000000000);
    }
require(toLocked.end >= locked_.end, "Only delegate to self or longer lock");
