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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 _copy_id_str_old(self):
        '''
        Return the string to execute ssh-copy-id
        '''
        if self.passwd:
            # Using single quotes prevents shell expansion and
            # passwords containing '$'
            return "{0} {1} '{2} -p {3} {4} {5}@{6}'".format(
                    'ssh-copy-id',
                    '-i {0}.pub'.format(self.priv),
                    self._passwd_opts(),
                    self.port,
                    self._ssh_opts(),
                    self.user,
                    self.host)
        return None