class Model:
    val = 1
    lst = [val for _ in range(3)]

print(Model.lst)

x = [1, 2, 3, 4, 5]
x[::2] = [10, 20, 30]
print(x)

print(all([]))

print(1 in [1, 2] == True)

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

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())