is_valid check
is_valid check


Former-commit-id: 6acd24cbd4198bcf1e561aeabc6b70ea4cdb8d7a
clab/dynet,shuheik/dynet,chunyang-wen/dynet,xunzhang/dynet,danielhers/dynet,clab/dynet,shuheik/dynet,chunyang-wen/dynet,danielhers/dynet,clab/cnn,clab/cnn,chunyang-wen/dynet,xunzhang/dynet,clab/cnn,danielhers/dynet,shuheik/dynet,xunzhang/dynet,danielhers/dynet,shuheik/dynet,danielhers/dynet,xunzhang/dynet,clab/dynet,shuheik/dynet,clab/dynet,clab/dynet,clab/dynet,danielhers/dynet,shuheik/dynet,shuheik/dynet,chunyang-wen/dynet,clab/dynet,danielhers/dynet