m4_if(b4_prefix, [yy], [],
[
// Take the name prefix into account.
#define yylex b4_prefix[]lex])[
/* First part of user declarations. */
m4_if(b4_prefix, [yy], [],
[
// Take the name prefix into account.
#define yylex b4_prefix[]lex])[
/* First part of user declarations. */