🕵️ Stack Trace Lineup

class Box:
    def __init__(self):
        self._v = 0
    @property
    def v(self):
        return self._v
    @v.setter
    def v(self, x):
        self._v = x * 2

b = Box()
b.value = 5
print(b.v)

Traceback (most recent call last):
  File "lineup.py", line 13, in <module>
    print(b.v)
AttributeError: 'Box' object has no attribute 'v' (did you mean: '_v'?)

import functools

@functools.cache
def slow(n):
    return n * 2

slow([1, 2, 3])

Traceback (most recent call last):
  File "lineup.py", line 7, in <module>
    slow([1, 2, 3])
    ~~~~^^^^^^^^^^
TypeError: unhashable type: 'list'

def factory():
    funcs = []
    for i in range(3):
        funcs.append(lambda: i)
    return funcs

print([f() for f in factory()])

# (no error — but the OUTPUT might surprise you)
[2, 2, 2]

data = {"a": 1, "b": 2, "c": 3}
for key in data:
    if key == "b":
        data["d"] = 4

Traceback (most recent call last):
  File "lineup.py", line 2, in <module>
    for key in data:
KeyError: 'd'

try:
    raise ValueError("first")
except ValueError as e:
    raise RuntimeError("second") from e

Traceback (most recent call last):
  File "lineup.py", line 2, in <module>
    raise ValueError("first")
ValueError: first

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "lineup.py", line 4, in <module>
    raise RuntimeError("second") from e
RuntimeError: second