for (i = 2; i < argc; i += 2) {
char *a, *b;
a = argv[i]; b = argv[i+1];
if (!b || strcmp(a, "-p") || get_sha1(b, parent_sha1[parents]))
usage(commit_tree_usage);
for (i = 2; i < argc; i += 2) {
char *a, *b;
a = argv[i]; b = argv[i+1];
if (!b || strcmp(a, "-p") || get_sha1(b, parent_sha1[parents]))
usage(commit_tree_usage);