def make_counters():
    counters = []

    for i in range(3):
        def counter():
            return i
        counters.append(counter)

    return counters


funcs = make_counters()
print([f() for f in funcs])

def append_to(num, target=[]):
    target.append(num)
    return target

print(append_to(1))
print(append_to(2))

def append_to(num, target=None):
    if target is None:
        target = []
    target.append(num)
    return target

x = {"key1": "value1 from x", "key2": "value2 from x"}
y = {"key2": "value2 from y", "key3": "value3 from y"}

# Старый способ (до 3.9)
z = {**x, **y}

# Новый способ (Python 3.9+)
z = x | y

print(z)
# {'key1': 'value1 from x', 'key2': 'value2 from y', 'key3': 'value3 from y'}