sort for linked lists python

1class Node:
2  def __init__(self):
3    self.data = None
4    self.next = None
5
6class LinkedList:
7  def __init__(self):
8    self.head = None
9
10  def addNode(self, data):
11    curr = self.head
12    if curr is None:
13      n = Node()
14      n.data = data
15      self.head = n
16      return
17
18    if curr.data > data:
19      n = Node()
20      n.data = data
21      n.next = curr
22      self.head = n
23      return
24
25    while curr.next is not None:
26      if curr.next.data > data:
27        break
28      curr = curr.next
29    n = Node()
30    n.data = data
31    n.next = curr.next
32    curr.next = n
33    return
34
35  def __str__(self):
36    data = []
37    curr = self.head
38    while curr is not None:
39      data.append(curr.data)
40      curr = curr.next
41    return "[%s]" %(', '.join(str(i) for i in data))
42
43  def __repr__(self):
44    return self.__str__()
45
46def main():
47  ll = LinkedList()
48  num = int(input("Enter a number: "))
49  while num != -1:
50    ll.addNode(num)
51    num = int(input("Enter a number: "))
52  c = ll.head
53  while c is not None:
54    print(c.data)
55    c = c.next