prep_io          7357 io.c               return prep_io(fd, rb_io_oflags_fmode(oflags), klass, path);
prep_io          7364 io.c               VALUE io = prep_io(fileno(f), fmode|FMODE_PREP|DEFAULT_TEXTMODE, klass, path);
prep_io          8044 io.c           		    write_io = prep_io(fw, FMODE_WRITABLE, rb_cFile, fn);
prep_io          8052 io.c           		ARGF.current_file = prep_io(fr, fmode, rb_cFile, fn);