RUBY_T_UNDEF      504 include/ruby/ruby.h #define T_UNDEF  RUBY_T_UNDEF
RUBY_T_UNDEF      524 include/ruby/ruby.h 	((type) == RUBY_T_UNDEF) ? ((obj) == RUBY_Qundef) : \
RUBY_T_UNDEF     1971 include/ruby/ruby.h 	if (obj == RUBY_Qundef) return RUBY_T_UNDEF;