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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 gets(self, key, default=None, cas_default=None):
 """ The memcached "gets" command for one key, as a convenience. Args: key: str, see class docs for details. default: value that will be returned if the key was not found. cas_default: same behaviour as default argument. Returns: A tuple of (value, cas) or (default, cas_defaults) if the key was not found. """

        defaults = (default, cas_default)
        return self._fetch_cmd(b'gets', [key], True).get(key, defaults)