🕵️ Stack Trace Lineup

def fib(n):
    if n < 2: return n
    return fib(n-1) + fib(n-2)

print(fib(-1))

# (no error — but the recursion descends forever in negative numbers)
# In practice this hits RecursionError after ~1000 frames.
RecursionError: maximum recursion depth exceeded

s = "hello"
for i, c in enumerate(s):
    print(i, c)

# (no error)
0 h
1 e
2 l
3 l
4 o

try:
    x = 1 / 0
except ZeroDivisionError:
    print("caught")
else:
    print("no error")
finally:
    print("always")

# (no error)
caught
always

with open("/tmp/does-not-exist.txt") as f:
    print(f.read())

Traceback (most recent call last):
  File "lineup.py", line 1, in <module>
    with open("/tmp/does-not-exist.txt") as f:
         ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: [Errno 13] Permission denied: '/tmp/does-not-exist.txt'

numbers = [1, 2, 3, 4, 5]
squared = [n ** 2 for n in numbers if n % 2 == 0]
print(squared)

# (no error)
[4, 16]