Made sig more efficient?
Made sig more efficient?


Former-commit-id: 8a3f2ba6c8dbf3e3c0509bdb80c54c11970ca6be
xunzhang/dynet,shuheik/dynet,xunzhang/dynet,clab/cnn,shuheik/dynet,clab/dynet,danielhers/dynet,chunyang-wen/dynet,shuheik/dynet,xunzhang/dynet,chunyang-wen/dynet,shuheik/dynet,danielhers/dynet,shuheik/dynet,clab/cnn,clab/dynet,chunyang-wen/dynet,clab/dynet,shuheik/dynet,clab/dynet,chunyang-wen/dynet,danielhers/dynet,danielhers/dynet,clab/dynet,danielhers/dynet,danielhers/dynet,clab/cnn,clab/dynet,danielhers/dynet,clab/dynet,shuheik/dynet,xunzhang/dynet