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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def merge_list(merged_list, items):
 """ Merges items into a list, appends ignoring duplicates but retaining the original order. This modifies the list and does not return anything. :param merged_list: List to append de-duplicated items to. :type merged_list: list :param items: Items to merge into the list. :type items: collections.Iterable """

    if not items:
        return
    merged_set = set(merged_list)
    merged_add = merged_set.add
    merged_list.extend(item
                       for item in items
                       if item not in merged_set and not merged_add(item))