def merge(from_, into):

    '''The into node is saved; the from_ node is deleted.'''

    for child in NodeIter(from_): into.appendChild(child)

    remove(from_)

def merge_adjacent(node):

    '''Repeatedly merges two nodes as long as they or their newly-adjacent

    children have the same tag name'''

    if node == None: return # base case

    for node_, next in [(node.previousSibling, node), (node, node.nextSibling)]:

        if node_ != None and next != None and node_.tagName == next.tagName:

            next_first = next.firstChild # save before merge

            merge(next, node_)

            merge_adjacent(next_first) # previousSibling is now node_.lastChild