def METHOD_NAME(landmarks, start_idx, stop_idx):
    start_landmarks = landmarks[start_idx]
    stop_landmarks = landmarks[stop_idx]
    delta = stop_landmarks - start_landmarks
    for idx in range(1, stop_idx - start_idx):
        landmarks[start_idx + idx] = start_landmarks + idx / float(stop_idx - start_idx) * delta
    return landmarks