def preprocess(self, payload: MultimodalData | None) -> MultimodalValue | None:
        """
        Parameters:
            payload: the text and list of file(s) entered in the multimodal textbox.
        Returns:
            Passes text value and list of file(s) as a {dict} into the function.
        """
        if payload is None:
            return None
        if self.file_types is not None:
            for f in payload.files:
                if not client_utils.is_valid_file(f.path, self.file_types):
                    raise Error(
                        f"Invalid file type: {f.mime_type}. Please upload a file that is one of these formats: {self.file_types}"
                    )
        return {
            "text": payload.text,
            "files": [f.path for f in payload.files],
        }

        Parameters:
            payload: the text and list of file(s) entered in the multimodal textbox.
        Returns:
            Passes text value and list of file(s) as a {dict} into the function.
        
gradio/components/multimodal_textbox.py