src/transformers/pipelines/base.py/PipelineDataFormat/from_str
class PipelineDataFormat:    def from_str(
        format: str,
        output_path: Optional[str],
        input_path: Optional[str],
        column: Optional[str],
        overwrite=False,
    ) -> "PipelineDataFormat":
        """
        Creates an instance of the right subclass of :class:`~transformers.pipelines.PipelineDataFormat` depending on
        :obj:`format`.

        Args:
            format: (:obj:`str`):
                The format of the desired pipeline. Acceptable values are :obj:`"json"`, :obj:`"csv"` or :obj:`"pipe"`.
            output_path (:obj:`str`, `optional`):
                Where to save the outgoing data.
            input_path (:obj:`str`, `optional`):
                Where to look for the input data.
            column (:obj:`str`, `optional`):
                The column to read.
            overwrite (:obj:`bool`, `optional`, defaults to :obj:`False`):
                Whether or not to overwrite the :obj:`output_path`.

        Returns:
            :class:`~transformers.pipelines.PipelineDataFormat`: The proper data format.
        """
        if format == "json":
            return JsonPipelineDataFormat(output_path, input_path, column, overwrite=overwrite)
        elif format == "csv":
            return CsvPipelineDataFormat(output_path, input_path, column, overwrite=overwrite)
        elif format == "pipe":
            return PipedPipelineDataFormat(output_path, input_path, column, overwrite=overwrite)
        else:
            raise KeyError(f"Unknown reader {format} (Available reader are json/csv/pipe)")