def format_items(x):
    """Returns a succinct summaries of all items in a sequence as strings"""
    x = np.asarray(x)
    timedelta_format = 'datetime'
    if np.issubdtype(x.dtype, np.timedelta64):
        x = np.asarray(x, dtype='timedelta64[ns]')
        day_part = (x[~pd.isnull(x)]
                    .astype('timedelta64[D]')
                    .astype('timedelta64[ns]'))
        time_needed = x[~pd.isnull(x)] != day_part
        day_needed = day_part != np.timedelta64(0, 'ns')
        if np.logical_not(day_needed).all():
            timedelta_format = 'time'
        elif np.logical_not(time_needed).all():
            timedelta_format = 'date'

    formatted = [format_item(xi, timedelta_format) for xi in x]
    return formatted