unique_in_order.md

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')
unique_in_order('ABBCcAD')
unique_in_order([1,2,2,3,3])

unique_in_order(iterable) # returns:

['A', 'B', 'C', 'D', 'A', 'B']
['A', 'B', 'C', 'c', 'A', 'D']
[1,2,3]

Solution:

def unique_in_order(iterable):
    previous_item = ""
    result = []
    for item in iterable:
        if item != previous_item:
            result.append(item)
        previous_item = item
    return result

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