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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 html(self):
 """ Returns ``innerHTML`` of whole page. On page have to be tag ``body``. .. versionadded:: 2.2 """

        try:
            body = self.get_elm(tag_name='body')
        except selenium_exc.NoSuchElementException:
            return None
        else:
            return body.get_attribute('innerHTML')