def _validate_framework_choice(framework: str):
        """
        Validates if the framework requested for the export is both correct and available, otherwise throws an
        exception.
        """
        if framework not in ["pt", "tf"]:
            raise ValueError(
                f"Only two frameworks are supported for ONNX export: pt or tf, but {framework} was provided."
            )
        elif framework == "pt" and not is_torch_available():
            raise RuntimeError("Cannot export model to ONNX using PyTorch because no PyTorch package was found.")
        elif framework == "tf" and not is_tf_available():
            raise RuntimeError("Cannot export model to ONNX using TensorFlow because no TensorFlow package was found.")

        Validates if the framework requested for the export is both correct and available, otherwise throws an
        exception.
        
dpkd/transformers/src/transformers/onnx/features.py