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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 cwd (self):
 """ Change to URL parent directory. Return filename of last path component. """

        path = self.urlparts[2].encode(self.filename_encoding, 'replace')
        dirname = path.strip('/')
        dirs = dirname.split('/')
        filename = dirs.pop()
        self.url_connection.cwd('/')
        for d in dirs:
            self.url_connection.cwd(d)
        return filename