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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 compare_config(self):
 """ Compare configuration to be merged with the one on the device. Compare executed candidate config with the running config and return a diff, assuming the loaded config will be merged with the existing one. :return: Config diff. """

        _show_merge = self._execute_config_show('show configuration merge')
        _show_run = self._execute_config_show('show running-config')

        diff = difflib.unified_diff(_show_run.splitlines(1)[2:-2], _show_merge.splitlines(1)[2:-2])
        return ''.join([x.replace('\r', '') for x in diff])