-struct psi_token *psi_token_cat(unsigned argc, ...);
-struct psi_token *psi_token_append(struct psi_token *T, unsigned argc, ...);
+void psi_token_copy_ctor(struct psi_token **src);
+struct psi_token *psi_token_cat(const char *sep, unsigned argc, ...);
+struct psi_token *psi_token_prepend(const char *sep, struct psi_token *T, unsigned argc, ...);
+struct psi_token *psi_token_append(const char *sep, struct psi_token *T, unsigned argc, ...);