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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 get_item_children(item):

 """Return a sorted list of all the children items of 'item'."""

    children = [item.child(index) for index in range(item.childCount())]
    for child in children[:]:
        others = get_item_children(child)
        if others is not None:
            children += others
    return sorted(children, key=lambda child: child.line)