def _integer_to_timestamp(arg, unit='s'):
    """
    Convert integer UNIX timestamp (at some resolution) to a timestamp type

    Parameters
    ----------
    unit : {'s', 'ms', 'us'}
      Second (s), millisecond (ms), or microsecond (us) resolution

    Returns
    -------
    timestamp : timestamp value expression
    """
    op = ops.TimestampFromUNIX(arg, unit)
    return op.to_expr()