def f(a, d={}):
    d[a] = d.get(a, 0) + 1
    return d

print(f("x"), end=" ")
print(f("x"))

def f(x):
    return {i: i**x for i in range(3)}

print(f(2)[1])

def f(a, b):
    a["val"] += b["val"]
    b = {"val": 0}

x = {"val": 1}
y = {"val": 2}
f(x, y)
print(x["val"], y["val"])

def f(s):
    s.add(4)

a = {1, 2, 3}
f(a)
print(sorted(a))

def g():
    return set("hello")

s = g()
print(len(s))

def combine(a, b):
    return a & b

x = {1, 2, 3}
y = {2, 3, 4}
print(combine(x, y))

result = [x**2 for x in range(10) if x % 2 == 0]
print(result)

result = {len(word) for word in ["hi", "hello", "world", "hi", "code"]}
print(result)

words = ["a", "bb", "ccc"]
result = {word: len(word) for word in words}
print(result)

matrix = [[1, 2, 3], [4, 5], [6]]
result = [x for row in matrix for x in row if x % 2 == 0]
print(result)

numbers = range(5)
result = {x: ('even' if x % 2 == 0 else 'odd') for x in numbers}
print(result)