Add flag option to select chains or fan-out write
Add flag option to select chains or fan-out write

linyvxiang/dfs,imotai/bfs,yvxiang/coverage_for_bfs,00k/ToyDFS,myawan/bfs-1,myawan/bfs-1,linyvxiang/dfs,yvxiang/dfs,baidu/bfs,lylei/dfs,bluebore/dfs,bluebore/bfs,bluebore/dfs,lylei/dfs,baidu/bfs,lylei/dfs,yvxiang/coverage_for_bfs,yvxiang/dfs,imotai/bfs,yvxiang/coverage_for_bfs,myawan/bfs-1,bluebore/dfs,lylei/dfs,baidu/bfs,baidu/bfs,00k/ToyDFS,yvxiang/coverage_for_bfs,myawan/bfs-1,yvxiang/dfs,bluebore/bfs,yvxiang/dfs,linyvxiang/dfs,bluebore/bfs,imotai/bfs