rb_io_check_writable 305 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 375 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 525 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 1436 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 2647 io.c               rb_io_check_writable(fptr);
rb_io_check_writable 596 marshal.c      	    rb_io_check_writable(fptr);