  A string representing a duration conforming to the ISO8601 standard,
    such as: P1W1DT13H23M34S
    P is the duration designator (for period) placed at the start of the duration representation.
    Y is the year designator that follows the value for the number of years.
    M is the month designator that follows the value for the number of months.
    W is the week designator that follows the value for the number of weeks.
    D is the day designator that follows the value for the number of days.
    T is the time designator that precedes the time components of the representation.
    H is the hour designator that follows the value for the number of hours.
    M is the minute designator that follows the value for the number of minutes.
    S is the second designator that follows the value for the number of seconds.

    Note the time designator, T, that precedes the time value.

    Matches moment.js, Luxon and DateFns implementations
    ,/. is valid for decimal places and +/- is a valid prefix
  