def flatten(t):list = []for i in t:if(type(i) != list and type(i) != tuple):list.append(i)else:list.extend(flatten(i))return list

Here is the function that I've written to flatten a list or a tuple that looks something like

l = ((5, (1,2), [[1],[2]]))

when I do

flatten(l)

I expected to get a list

[5, 1, 2, 1, 2]

but I instead get

[5, 1, 2, [[1], [2]]]

I am not really sure why this happens because

    else:list.extend(flatten(i))

this part of the code will retrieve the int inside the third element of the tuple which is [[1],[2]] by calling it recursively. What am I missing here?

Thanks

You've assigned the built-in list to a list instance in your function, so the type check no longer works properly for list objects.

You should use a different name for the accumulator list, say, lst:

def flatten(t):lst = []for i in t:if type(i) != list and type(i) != tuple:lst.append(i)else:lst.extend(flatten(i))return lst

OTOH, you could do both checks at once using isinstance which also ensures that the objects you're running your checks against are actually types:

...
if not isinstance(i, (list, tuple)):...