def put_comma(alignment, min_threshold: float = 0.5):
    """
    Put comma in alignment from force alignment model.

    Parameters
    -----------
    alignment: List[Dict[text, start, end]]
    min_threshold: float, optional (default=0.5)
        minimum threshold in term of seconds to assume a comma.

    Returns
    --------
    result: List[str]
    """
    r = []
    for no, row in enumerate(alignment):
        if no > 0:
            if alignment[no]['start'] - alignment[no-1]['end'] >= min_threshold:
                r.append(',')

        r.append(row['text'])
    r.append('.')
    return r