def gen(n):
    for i in n:
        yield i
g = gen('abcd')
l = len(list(g))
print(next(g), l)

def f(a, b, c):
    return (a + 2*b) ** c
w = {"a": 1, "b": 2, "c": 3}
print(f(**w))

ranks = {'aaa': 1, 'bbbb': 2}
rank_dict = {rank: name for name, rank in ranks.items()}
set_len = {len(name) for name in rank_dict.values()}
print(rank_dict, set_len)

def f(seq):
    if not seq:  
        return [seq]
    else:
        res = []
        for i in range(len(seq)):
            rest = seq[:i] + seq[i+1:] 
            for x in f(rest):
                res.append(seq[i:i+1] + x)
        return res
a = f([1, 2])
b = f([1, 2, 3, 4, 5])
print(a, len(b))

def f(*seqs):
    seqs = [list(S) for S in seqs]
    res = []
    while all(seqs):
        res.append(tuple(S.pop(0) for S in seqs))
    return res
s1, s2 = 'abc', '12345'
print(list(zip(s1, s2)) == f(s1, s2))

def f(*seqs, pad=None):
    seqs = [list(S) for S in seqs]
    res = []
    while any(seqs):
        res.append(tuple((S.pop(0) if S else pad) for S in seqs))
    return res

s1, s2 = 'abc', '12345'
print(list(zip(s1, s2)) == f(s1, s2))

def f(*seqs):
    minlen = min(len(s) for s in seqs)
    return [tuple(s[i] for s in seqs) for i in range(minlen)]

s1, s2 = 'ab' , 'xyz'
print(f(s1, s2))

def f(seq):
    if not seq:
        yield seq
    else:
        for i in range(len(seq)):
            rest = seq[:i] + seq[i+1:]
            for x in f(rest):
                yield seq[i:i+1] + x
a = [*f(['a', 'b'])]
b = [*f(['a', 'b', 'c', 'd'])]
print(a, len(b))

_ = [i for i in range(10)]
print(i)

def f(seq):
    for i in range(len(seq)):
        yield seq[i:] + seq[:i]
print((list(f('123'))))