The Haunted List

The function append_to should take an element and an optional list, append the element to it, and return the result.

When called without a second argument, it should always start fresh with an empty list.

But something strange is happening — it seems to remember values between calls. How?

# your fix

+ must use None

hint 2after hint 1

hint 3after hint 2

solution

Read the code. Before running anything: what does the last line below give?

def append_to(element, to=[]):

to.append(element)

return to

>>> append_to(1)

>>> append_to(2)