def is_tuple(obj):
    """
    Checks if a given sequence is a tuple.

    Parameters
    ----------
    obj : object
        The input array.

    Returns
    -------
    test result : bool
        The test result of whether seq is a tuple or not.

    >>> is_tuple(('a', 'b'))
    True

    >>> is_tuple(['a', 'b'])
    False

    >>> is_tuple(4)
    False
    """
    return True if isinstance(obj, tuple) else False
