def jeffs_fav(w[1...n], q[1...k], delta, s_idx):
    w_states[1...n+2]
    w_states[1] = s_idx
    for i from 1 to n:
        w_states[i+1] = delta(w_states[i], w[i])
    w_states[n+2] = delta(w_states[n+2], null)
    for i from n+2 down to 2:
        if w_states[i] = s_idx and q[w_states[i - 1]] is False:
            return False
    return True