val = 10

def update():
    global val
    val = 20
    del val

update()

try:
    print(val)
except NameError:
    print("NameError")

def swap(a, b):
    return b, a

x, y = 10, 20
x, y = swap(x, y)
x, y = swap(y, x)
print(x + y)

x = 1

def func():
    x = 2
    print(globals()['x'])

func()

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

print(-11 % 3, 11 % -3)

class A:
    x = 1

class B(A):
    pass

class C(A):
    pass

B.x = 2
A.x = 3

print(C.x)

val = 10

def update():
    global val
    val = 20
    del val

update()

try:
    print(val)
except NameError:
    print("NameError")

def func(a, b, c, d):
    return a + b * c - d

args = [2, 3]
kwargs = {'c': 4, 'd': 5}
result = func(*args, **kwargs)
print(result)

class Point:
    __slots__ = ['x', 'y']

p = Point()
p.x = 1
p.z = 2
print(p.x)

colors = ['red', 'green', 'blue']
colors.insert(1, colors.pop())
colors.reverse()
print(colors[0])