def get_io_dtype(self, io_name: str) -> Optional[str]:
        """Get the data type of an input/output.

        :param io_name: name of the input/output.
        :return: data type of the input/output.
        """
        elem_type = self.get_io_elem_type(io_name)
        return str(onnx.helper.tensor_dtype_to_np_dtype(elem_type)) if elem_type else None
Get the data type of an input/output.

        :param io_name: name of the input/output.
        :return: data type of the input/output.
        
olive/passes/onnx/onnx_dag.py