def f():
    _x = None
    def g(x=None):
        nonlocal _x
        if x is None:
            return _x
        _x = x
    return g
g = f()
print(g(), g(10), g(), g(5), g())

def f(x):
    y = x ** 2
    return y
print(*f.__code__.co_varnames)

def f(x, y):
    f.y = y
    f.z = f.y
    return x
print(f(1, 2), [x for x in dir(f) if not x.startswith('__')])

def f(arr):
    return 0 if not arr else arr[0] + f(arr[1:])
print(f(('a', 'b', 'c', 'd')))

def f(arr):
    return arr[0] if len(arr) == 1 else arr[0] + f(arr[1:])
print(f(('a', 'b', 'c', 'd')))

def f(arr):
    first, *rest = arr
    return first if not rest else first + f(rest)
print(f(('H', 'e', 'l', 'l', 'o')))

def f(a: int, b: float) -> int:
         return a * int(b) 
print(f(5, 2.1))

def func(a: str, b: int):
    return a + b 
func(1, 2)
for arg in sorted(func.__annotations__):
    print(arg, func.__annotations__[arg])
    break

def f(x, y):
    z = x ** y
    return z
print(f.__code__.co_argcount)

def f(arr):
    s = 0
    for x in arr:
        if not isinstance(x, list):
            s += x
        else:
            s += f(x)
    return s
print(f([1, [2, [3, [4, [5]]]]]))

from collections.abc import Iterable
def f(arr):
    s = 0
    items = list(arr)
    while items:
        first = items.pop(0)
        if not isinstance(first, Iterable):
            s += first
        else:
            items.extend(first)
    return s
print(f((1, (2, (3, (4, (5)))))))