+#ifndef EPOCH_H
+#define EPOCH_H
+
+
+// return codes for emitter_func
+#define STOP 0
+#define CONTINUE 1
+#define DO 2
+typedef int (*emitter_func) (struct commit *);
+
+int sort_list_in_merge_order(struct commit_list *list, emitter_func emitter);
+
+#define UNINTERESTING (1u<<2)
+#define BOUNDARY (1u<<3)
+#define VISITED (1u<<4)
+#define DISCONTINUITY (1u<<5)
+#define DUPCHECK (1u<<6)
+
+
+#endif /* EPOCH_H */