Gut-feelings and code go together…

what-do-you-expect-to-happen.py

# Here's a simple (and silly, but it's an example) function definition in Python:

def append(value, l=[]):
	"""Append a value to a list, return that list."""
	l.append(value)
	return l


print(append(27))  # [27]
print(append(42))  # ?
print(append(96))  # ?

# Clguba shapgvba nethzrag qrsnhygf ner cebprffrq bapr, ng qrpynengvba gvzr, naq erpbeqrq ntnvafg gur shapgvba.
# Vg pna or uvtuyl aba-boivbhf gb  arj qrirybcref gung gur qrsnhygf nera'g er-rinyhngrq ba rnpu pnyy.

# Searchable term: mutable defaults