I know how the extend() method works. But when it comes to this program I am not able to figure out the flow of execution. Could

Question

def flatten(arr):
resultArr = []
for custItem in arr:
if type(custItem) is list:
resultArr.extend(flatten(custItem))
else:
resultArr.append(custItem)
return resultArr
print(flatten([[1,2,[3]]]))
output- [1,2,3]

Answer 1

It's just recursion, the code will check for the type of each element of a given list, and if this type is `list`: the function will call itself to work on this new `list` applying the same rule until it does not extend anymore, so it will just consume every list it founds before jumping to the next element.

Answer 2

Ervis Meta - SoloHelper
Could u pls explain with an example. It will be really helpful !