Why am I getting an error in the following code ?

Question

def nestedEvenSum(obj, s=0):
result = []
for key in obj:
if type(obj[key]) is int and obj[key]%2==0:
result.append(obj[key])
elif type(obj[key]) is dict:
result = result + nestedEvenSum(obj[key])
return sum(result)

obj = {
"a": 2,
"b": {"b": 2, "bb": {"b": 3, "bb": {"b": 2}}},
"c": {"c": {"c": 2}, "cc": 'ball', "ccc": 5},
"d": 1,
"e": {"e": {"e": 2}, "ee": 'car'}
}
print(nestedEvenSum(obj))

In line 7 I am getting an error saying
TypeError: can only concatenate list (not "int") to list

Answer 1

https://code.sololearn.com/cw0yI2Cg3Prl/?ref=app

Answer 2

Your func on elif brunch returns int sum and can't adds to array, only in a such way:
result += [ nestedEvenSum(obj[key])) ],
or use
result.append(nestedEvenSum(obj[key]))

Answer 3

Vitaly Sokol
Hy, thanks for your solution but I want to know the reason for the error? Why am I getting typerror