id_to_r            27 complex.c          id_real_p, id_to_f, id_to_i, id_to_r, id_to_s;
id_to_r          1395 complex.c          id_to_r = rb_intern("to_r");
id_to_r          1414 rational.c     #define f_to_r(x) rb_funcall(x, id_to_r, 0)