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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 composite_join(separator, items):
 """ Join a list of items with a separator. This is used in joining strings, responses and Composites. The output will be a Composite. """

        output = Composite()
        first_item = True
        for item in items:
            # skip empty items
            if not item:
                continue
            # skip separator on first item
            if first_item:
                first_item = False
            else:
                output.append(separator)
            output.append(item)
        return output