+/* Break up str on characters in brksep, terminated by brkterm.
+ * Each character in str that exists in brksep is replace with a null byte.
+ * Processing stops at the first character in str that exists in brkterm.
+ * Directly mutates str.
+ * Returns pointer to private, static array of pointers into str. */
+char *const *brkstring(char *str, char const *brksep, char const *brkterm) NONNULL(1);