int show_sample_fmts(void *optctx, const char *opt, const char *arg);
/**
+ * Print a listing containing all the color names and values recognized
+ * by the program.
+ */
+void show_colors(void *optctx, const char *opt, const char *arg);
+
+/**
* Return a positive value if a line read from standard input
* starts with [yY], otherwise return 0.
*/