(nums)
return i
:type nums: List[int]
    :rtype: int
:type nums: List[int]
    :rtype: int
: type nums : List [ int ] : rtype : int
def single_number(nums):
    """
    :type nums: List[int]
    :rtype: int
    """
    i = 0
    for num in nums:
        i ^= num
    return i
def single_number ( nums ) : i = 0 for num in nums : i ^= num return i