file.c:136
static VALUE
rb_stat_cmp(self, other)
    VALUE self, other;
{
    if (rb_obj_is_kind_of(other, rb_obj_class(self))) {
	time_t t1 = get_stat(self)->st_mtime;
	time_t t2 = get_stat(other)->st_mtime;
	if (t1 == t2)
	    return INT2FIX(0);
	else if (t1 < t2)
	    return INT2FIX(-1);
	else
	    return INT2FIX(1);
    }
    return Qnil;
}
