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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 plain(self):
 """ Get a string representation of this XML document. @return: A I{plain} string. @rtype: basestring """

        s = []
        s.append(self.DECL)
        root = self.root()
        if root is not None:
            s.append(root.plain())
        return ''.join(s)