print(any([0, "", False]))

class A:
    x = 1

class B(A):
    pass

class C(A):
    pass

B.x = 2
A.x = 3

print(C.x)

def modify(x, y=[]):
    y.append(x)
    return sum(y)

result = modify(5) + modify(7) + modify(4)
print(result)

gen = (x for x in range(3))
print(list(gen), list(gen))

class Matrix:
    def __init__(self, data):
        self.data = data
    
    def __add__(self, other):
        return Matrix([[self.data[i][j] + other.data[i][j] 
                       for j in range(len(self.data[0]))] 
                       for i in range(len(self.data))])
    
    def sum(self):
        return sum(sum(row) for row in self.data)

m1 = Matrix([[1, 2], [3, 4]])
m2 = Matrix([[5, 6], [7, 8]])
result = m1 + m2
print(result.sum())

def make_counter():
    count = 0
    def increment():
        nonlocal count
        count += 1
        return count
    return increment

c1 = make_counter()
c2 = make_counter()
c1()
print(c1(), c2())

lst = [x for x in range(10) if x % 2 == 0 if x % 3 == 0]
print(lst)

d = {'a': 1, 'b': 2, 'c': 3}
try:
    for k in d:
        del d[k]
    print(len(d))
except RuntimeError:
    print("RuntimeError")

from itertools import islice

def infinite_seq():
    n = 1
    while True:
        yield n
        n *= 2

gen = infinite_seq()
result = list(islice(gen, 5))
print(sum(result))

gen = (x for x in range(3))
print(list(gen), list(gen))

d = {'a': 1, 'b': 2, 'c': 3}
try:
    for k in d:
        del d[k]
    print(len(d))
except RuntimeError:
    print("RuntimeError")