f_to_s             48 ext/date/date_core.c #define f_to_s(x) rb_funcall(x, rb_intern("to_s"), 0)
f_to_s             28 ext/date/date_parse.c #define f_to_s(x) rb_funcall(x, rb_intern("to_s"), 0)
f_to_s             38 rational.c     #define f_to_s rb_obj_as_string