(self, index, key_indices)
Return data of an example by keys

        Args:
            index (int): An index of an example.
            key_indices (tuple of ints): A tuple of indices of requested keys.

        Returns:
            tuple of data
Return data of an example by keys
Return data of an example by keys
def get_example_by_keys(self, index, key_indices):
        """Return data of an example by keys

        Args:
            index (int): An index of an example.
            key_indices (tuple of ints): A tuple of indices of requested keys.

        Returns:
            tuple of data
        """
        raise NotImplementedError
def get_example_by_keys ( self , index , key_indices ) : raise NotImplementedError