+ * @str: (array length=len) (element-type uint8_t): a string to parse
+ * @len: length of @str, or -1 if string is %NULL terminated
+ * @variation: (out): the #hb_variation_t to initialize with the parsed values
+ *
+ * Parses a string into a #hb_variation_t.
+ *
+ * The format for specifying variation settings follows. All valid CSS
+ * font-variation-settings values other than 'normal' and 'inherited' are also
+ * accepted, though, not documented below.
+ *
+ * The format is a tag, optionally followed by an equals sign, followed by a
+ * number. For example `wght=500`, or `slnt=-7.5`.
+ *
+ * Return value:
+ * %true if @str is successfully parsed, %false otherwise