+/* Append VALUE to the current value of KEY, using muscle_grow. But
+ in addition, issue a synchronization line for the location LOC. */
+
+void muscle_code_grow (const char *key, const char *value, location loc);
+
+
+/* MUSCLE is an M4 list of pairs. Create or extend it with the pair
+ (A1, A2) after escaping both values with digraphs. Note that because the
+ muscle values are output *double* quoted, one needs to strip the first level
+ of quotes to reach the list itself. */