-# Mimic muscle_percent_define_get in ../src/muscle_tab.h exactly. That is, if
-# the %define variable VARIABLE is defined, emit its value. Also, record
+# Declare that VARIABLE was used.
+m4_define([b4_percent_define_use],
+[m4_define([b4_percent_define_bison_variables(]$1[)])dnl
+])
+
+# b4_percent_define_get(VARIABLE, [DEFAULT])
+# ------------------------------------------
+# Mimic muscle_percent_define_get in ../src/muscle-tab.h. That is, if
+# the %define variable VARIABLE is defined, emit its value. Contrary
+# to its C counterpart, return DEFAULT otherwise. Also, record