langchain/document_loaders/onedrive.py/_SupportedFileTypes/fetch_mime_types
class _SupportedFileTypes:    def fetch_mime_types(self) -> Dict[str, str]:
        mime_types_mapping = {}
        for file_type in self.file_types:
            if file_type.value == "doc":
                mime_types_mapping[file_type.value] = "application/msword"
            elif file_type.value == "docx":
                mime_types_mapping[
                    file_type.value
                ] = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"  # noqa: E501
            elif file_type.value == "pdf":
                mime_types_mapping[file_type.value] = "application/pdf"
        return mime_types_mapping