def duration(message, wpm, output='timedelta', word_ref=WORD, word_spaced=False):
    """
    Calculate duration to send a message at a given code speed
    (calculated using reference word PARIS)

    Parameters
    ----------
    word : string
    wpm : int or float - word per minute
    output : String - type of output
        'timedelta'
        'float'
        'decimal'
    word : string - reference word (PARIS by default)
    word_spaced : bool - calculate with spaces between 2 words (default is False)

    Returns
    -------
    duration : timedelta or float or decimal.Decimal - duration of the word `word`

    >>> duration(_repeat_word('PARIS', 5), 5, word_spaced=True)
    datetime.timedelta(0, 60)

    >>> duration('PARIS', 15)
    datetime.timedelta(0, 3, 440000)

    >>> duration('SOS', 15)
    datetime.timedelta(0, 2, 160000)
    """
    elt_duration = wpm_to_duration(wpm, output=output, word_ref=word_ref)
    word_length = mlength(message, word_spaced=word_spaced)
    return word_length * elt_duration