hash.c:837
static VALUE
rb_hash_has_value(hash, val)
    VALUE hash;
    VALUE val;
{
    VALUE data[2];

    data[0] = Qfalse;
    data[1] = val;
    st_foreach(RHASH(hash)->tbl, rb_hash_search_value, (st_data_t)data);
    return data[0];
}
