def _describe_timeseries(ts):
    """
    Describes a cmf timeseries with its start, end, step, min, mean and max.

    :param: ts: a cmf.timeseries
    :return: None
    """
    if ts:
        return (
            '{count} values from {start:%Y-%m-%d} to {end:%Y-%m-%d} step {step}, min/mean/max  {min:0.5g} / {mean:0.5g} / {max:0.5g}'
            .format(count=len(ts), start=ts.begin.AsPython(), end=ts.end.
            AsPython(), step=ts.step, min=ts.min(), mean=ts.mean(), max=ts.
            max()))
    else:
        return '~'
