extern int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def);
extern void prepare_revision_walk(struct rev_info *revs);
extern struct commit *get_revision(struct rev_info *revs);
extern int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def);
extern void prepare_revision_walk(struct rev_info *revs);
extern struct commit *get_revision(struct rev_info *revs);