🕵️ Stack Trace Lineup

from typing import overload

@overload
def proc(x: int) -> int: ...
@overload
def proc(x: str) -> str: ...

def proc(x):
    return x * 2

print(proc([1, 2]))

# (no error — typing.overload is decorator-only documentation,
# no runtime dispatch — list * 2 doubles the list)
[1, 2, 1, 2]

import contextlib

@contextlib.contextmanager
def tag(name):
    print(f"<{name}>")
    yield
    print(f"</{name}>")

with tag("b"):
    print("hello")

# (no error)
<b>
hello
</b>

name = "ada"
prefix = b"user:"
print(prefix + name)

Traceback (most recent call last):
  File "lineup.py", line 3, in <module>
    print(prefix + name)
          ~~~~~~~^~~~~~~
TypeError: unsupported operand type(s) for +: 'bytes' and 'str'

from dataclasses import dataclass, replace

@dataclass(frozen=True)
class Point:
    x: int
    y: int

p = Point(1, 2)
p2 = replace(p, x=10)
print(p2)

# (no error — replace() is the canonical way to evolve frozen dataclasses)
Point(x=10, y=2)

from enum import Enum

class Color(Enum):
    RED = 1
    BLUE = 1  # duplicate value

print(Color.RED is Color.BLUE)

# (no error — Enum aliases duplicates by default)
True