/* Looking up value labels. */
const char *val_labs_find (const struct val_labs *, const union value *);
-const struct val_lab *val_labs_lookup (const struct val_labs *,
+struct val_lab *val_labs_lookup (const struct val_labs *,
const union value *);
/* Basic properties. */
/* Adding value labels. */
bool val_labs_add (struct val_labs *, const union value *, const char *);
void val_labs_replace (struct val_labs *, const union value *, const char *);
-void val_labs_remove (struct val_labs *, const struct val_lab *);
+void val_labs_remove (struct val_labs *, struct val_lab *);
/* Iterating through value labels. */
const struct val_lab *val_labs_first (const struct val_labs *);