Convert arrays of datetime.datetime and datetime.timedelta objects into
    datetime64 and timedelta64, according to the pandas convention.

def _possibly_convert_objects(values):
    """Convert arrays of datetime.datetime and datetime.timedelta objects into
    datetime64 and timedelta64, according to the pandas convention.
    """
    return np.asarray(pd.Series(values.ravel())).reshape(values.shape)