+/*
+ * `type`::
+ * holds the type of the option, you must have an OPTION_END last in your
+ * array.
+ *
+ * `short_name`::
+ * the character to use as a short option name, '\0' if none.
+ *
+ * `long_name`::
+ * the long option name, without the leading dashes, NULL if none.
+ *
+ * `value`::
+ * stores pointers to the values to be filled.
+ *
+ * `argh`::
+ * token to explain the kind of argument this option wants. Keep it
+ * homogenous across the repository.
+ *
+ * `help`::
+ * the short help associated to what the option does.
+ * Must never be NULL (except for OPTION_END).
+ * OPTION_GROUP uses this pointer to store the group header.
+ *
+ * `flags`::
+ * mask of parse_opt_option_flags.
+ * PARSE_OPT_OPTARG: says that the argument is optionnal (not for BOOLEANs)
+ * PARSE_OPT_NOARG: says that this option takes no argument, for CALLBACKs
+ *
+ * `callback`::
+ * pointer to the callback to use for OPTION_CALLBACK.
+ *
+ * `defval`::
+ * default value to fill (*->value) with for PARSE_OPT_OPTARG.
+ * CALLBACKS can use it like they want.
+ */