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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 url_to_text(self, url):
        '''
        Download PDF file and transform its document to string.

        Args:
            url:   PDF url.

        Returns:
            string.

        '''
        path, headers = urllib.request.urlretrieve(url)
        return self.path_to_text(path)