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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cmd():
 """Implementation of time subcommand. Other Parameters: conf.time conf.core """

    sdat = StagyyData(conf.core.path)
    if sdat.tseries is None:
        return

    if conf.time.fraction is not None:
        if not 0 < conf.time.fraction <= 1:
            raise InvalidTimeFractionError(conf.time.fraction)
        conf.time.tend = None
        t_0 = sdat.tseries.iloc[0].loc['t']
        t_f = sdat.tseries.iloc[-1].loc['t']
        conf.time.tstart = (t_0 * conf.time.fraction +
                            t_f * (1 - conf.time.fraction))

    lovs = misc.list_of_vars(conf.time.plot)
    if lovs:
        plot_time_series(sdat, lovs)

    if conf.time.compstat:
        compstat(sdat, conf.time.tstart, conf.time.tend)