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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 remove_nesting(dom, tag_name):
 """ Unwrap items in the node list that have ancestors with the same tag. """

    for node in dom.getElementsByTagName(tag_name):
        for ancestor in ancestors(node):
            if ancestor is node:
                continue
            if ancestor is dom.documentElement:
                break
            if ancestor.tagName == tag_name:
                unwrap(node)
                break