002. Codewars 之 Unique In Order

Implement the function unique_in_order which takes as argument a sequence and returns a list of items without any elements with the same value next to each other and preserving the original order of elements.
For example:

unique_in_order('AAAABBBCCDAABBB') == ['A', 'B', 'C', 'D', 'A', 'B']
unique_in_order('ABBCcAD')         == ['A', 'B', 'C', 'c', 'A', 'D']
unique_in_order([1,2,2,3,3])       == [1,2,3]

def unique_in_order(iterable):
    pass

Solution:

def unique_in_order(iterable):
    pre_item = None
    result = []
    for item in iterable:
        if item != pre_item:
            result.append(item)
            pre_item = item
    return result