+/* Randomly shuffles an array of items. */
+void shuffle(void *array, int nelts, int eltsize, random_state *rs);
+
+/* Draw a rectangle outline, using the frontend's draw_line. */
+void draw_rect_outline(frontend *fe, int x, int y, int w, int h,
+ int colour);
+
+/*
+ * dsf.c
+ */
+int dsf_canonify(int *dsf, int val);
+void dsf_merge(int *dsf, int v1, int v2);
+