def concat(self, other: FlatData[DataT]) -> IDataset[DataT]:
        """Concatenation

        :param other: other dataset
        :return:
        """
        if (
            isinstance(other, ConstantSequence)
            and self._constant_value == other._constant_value
        ):
            return ConstantSequence(self._constant_value, len(self) + len(other))
        else:
            return FlatData([self, other])
Concatenation

        :param other: other dataset
        :return:
        
avalanche/benchmarks/utils/flat_data.py