python中的条件赋值判断语句语法

c = a if a > b else b

summary = content[:100] if item[‘is_html'] else “”

(c = a > b and [a] for [b])[0]​

summary = item[‘is_html'] and content[:100] or “”

sum_buf = 0
for i in buf:
    if i is not None:
        sum_buf += i[0]

sum_buf = 0:
    for i in buf:
        sum_buf += i[0] if i else 0

sum_buf = sum([i[0] for i in buf if i])

buf = []
a = buf.pop() if buf else 0
# 这里a=0
# 做buf.pop()操作前先进行if判断

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution(object):
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        flag = False
        res = ListNode(0)
        _res = res
        while True:
            if l1 is None and l2 is None:
                if flag is 0:
                    p.next = None
                else:
                    _res.val += flag
                return res
            elif l1 is None:
                val, flag = self.__add(l2.val, flag)
                _res.val += val
                _res.next = ListNode(0)
                p = _res
                _res, l2 = _res.next, l2.next
            elif l2 is None:
                val, flag = self.__add(l1.val, flag)
                _res.val += val
                _res.next = ListNode(0)
                p = _res
                _res, l1 = _res.next, l1.next
            else:
                val, flag = self.__add(l1.val, l2.val, flag)
                _res.val += val
                _res.next = ListNode(0)
                p = _res
                _res, l1, l2 = _res.next, l1.next, l2.next
    def __add(self, *args):
        add = sum(args)
        carry = add//10
        return add-10*carry, carry

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        dummy = p = ListNode(None)
        s = 0
        while l1 or l2 or s:
            s += (l1.val if l1 else 0) + (l2.val if l2 else 0)
            p.next = ListNode(s % 10)
            p = p.next
            s //= 10
            l1 = l1.next if l1 else None
            l2 = l2.next if l2 else None
        return dummy.next