def convert_ann_to_seq_label(ann):
    """Convert structure annotation with integer time positions (given in indices)
    into label sequence

    Notebook: C4/C4S5_Evaluation.ipynb

    Args:
        ann: Annotation (list  [[s,t,'label'], ...], with s,t being integers)

    Returns:
        X: Sequencs of labels
    """
    X = []
    for seg in ann:
        K = seg[1] - seg[0]
        for k in range(K):
            X.append(seg[2])
    return X