n = 3
while n > 0:
    n -= 1
    if n == 1:
        break
else:
    print("A", end=" ")
print(n)

d = {True: 'a', 1: 'b', False: 'c', 0: 'd'}
print(len(d))

d = {'a': 1}
print(d.setdefault('a', 2), d.setdefault('b', 3))

d = dict.fromkeys(['x', 'y'], [])
d['x'].append(1)
print(d['y'])

lst = [[1, 2], [3, 4]]
print(sum(lst, []))

d = {True: 'a', 1: 'b', False: 'c', 0: 'd'}
print(len(d))

text = "A  B"
print(len(text.split()), len(text.split(" ")))

def my_func():
    return "Hello"

my_func.custom_attr = 5
print(my_func.custom_attr)

class MetaClass(type):
    def __new__(cls, name, bases, dct):
        dct['meta_value'] = 100
        return super().__new__(cls, name, bases, dct)
    
    def __init__(cls, name, bases, dct):
        cls.meta_value += len(name)

class A(metaclass=MetaClass):
    pass

class B(metaclass=MetaClass):
    pass

print(A.meta_value + B.meta_value)

t = (1, 2, [3, 4])
t[2].append(5)
print(t)