def all_ints(lst):
    ''' (list) -> bool

    Return True iff all elements in lst are ints.

    >>> all_ints([1, 2])
    True
    '''
    ok = True
    for s in lst:
        if not isinstance(s, int):
            ok = False
    return ok


def is_tuple_of_str_list(t, func_name):
    ''' (object, str) -> NoneType

    Check whether t is a 2-element tuple where the first element is a string
    and the second element is a 4-element list of ints.
    '''
    assert (isinstance(t, tuple) and len(t) == 2 and isinstance(t[0], str) \
           and isinstance(t[1], list) and len(t[1]) == 4 \
           and all_ints(t[1])
           ), \
           '{0} should return tuple of (str, list of four ints), but returned \
           {1}.'.format(func_name, t)


def is_tuple_of_str_None(t, func_name):
    '''(object, str) -> NoneType

    Check whether t is a 2-element tuple where the first element is a string
    and the second element is None.
    '''
    assert isinstance(t, tuple) and len(t) == 2 and isinstance(t[0], str) \
           and t[1] is None, \
           '{0} should return tuple of (str, NoneType), but returned \
           {1}.'.format(func_name, t)