Сделать код "красивее"

def lucky_sum(a, b, c):
  sum = 0 
  if a != 13:
     sum += a
  if b != 13 and a != 13:
     sum += b
  if c != 13 and b != 13 and a != 13:
     sum += c
  return sum

>>> from itertools import takewhile
>>> def lucky_sum(*args):
...     return sum(takewhile(lambda arg: arg != 13, args))
... 
>>> lucky_sum(1,2,3)
6
>>> lucky_sum(1,2,13)
3
>>> lucky_sum(1,13,2)
1
>>> lucky_sum(13,1,2)
0
>>>

>>> def broken_lucky(a, b, c):
...     return sum(takewhile(lambda arg: arg != 13, locals().values()))
... 
>>> broken_lucky(1,2,3)
6
>>> broken_lucky(1,2,13)
1
>>> broken_lucky(1,13,2)
3
>>>

>>> def lucky_sum(a, b, c):
...     return sum(takewhile(lambda arg: arg != 13, [a,b,c]))
...

>>> from itertools import takewhile
>>> from functools import partial
>>> from operator import ne
>>> def lucky_sum(*args):
...     return sum(takewhile(partial(ne, 13), args))
... 
>>>

>>> import xml.etree.ElementTree as etree
>>> xml = '''<?xml version="1.0" encoding="UTF-8"?><hero><name>Drikins</name><godname>Index</godname><gender>male</gender><gold_approx>ни одного</gold_approx><level>13</level><max_health>148</max_health><inventory_max_num>13</inventory_max_num><motto>За Годвилль!</motto><clan></clan><clan_position>патриарх</clan_position><alignment>нейтральный</alignment><quest>выполнить недопустимую операцию</quest><bricks_cnt>9</bricks_cnt><inventory></inventory></hero>'''
>>> tree = etree.fromstring(xml)
>>> for name in tree.findall('name'): # ищем все элементы name
...     print(name.text)
... 
Drikins
>>>

#!/usr/bin/env python3
 
def func(a, b, c):
    s = 0
    for i in a, b, c:
        if i == 13:
            break
        s += i
    return s
 
print(func(1, 2, 3))
print(func(13, 2, 3))
print(func(1, 13, 3))
print(func(1, 2, 13))