Why am I getting an error If changes the way of sorting the array

Question

1).class Small:
def __init__(self,arr):
self.arr=arr
def func(self):
self.arr=sorted(self.arr)
return self.arr[0]+self.arr[1]
i = Small(list(map(int,input("Enter the values:").split(" "))))
print(i.func())
2).class Small:
def __init__(self,arr):
self.arr=arr
def func(self):
self.arr=self.arr.sort()
return self.arr[0]+self.arr[1]
i = Small(list(map(int,input("Enter the values:").split(" "))))
print(i.func())

Answer 1

This statement:

self.arr=self.arr.sort()

sorts self.arr in place, and then sets self.arr to None.

Just remove "self.arr=" and it should behave like the first version