def METHOD_NAME(
    self, char_pred: torch.Tensor, char_target: torch.Tensor
) -> float:
    """Calculate sentence-level WER score.
    Args:
        char_pred: Prediction character sequences. (B, ?)
        char_target: Target character sequences. (B, ?)
    Returns:
        : Average sentence-level WER score
    """
    import editdistance
    distances, lens = [], []
    for i, char_pred_i in enumerate(char_pred):
        pred = char_pred_i.split()
        target = char_target[i].split()
        distances.append(editdistance.eval(pred, target))
        lens.append(len(target))
    return float(sum(distances)) / sum(lens)