file method
Implementation
Future<void> file(String path, {String? mimeType}) async {
final bytes = File(path).readAsBytesSync();
final mime = mimeType ?? lookupMimeType(path);
if (mime == null) {
return internalServerError(message: "mime-type can't resolved.");
}
headers
..contentLength = bytes.length
..set('content-type', mime);
add(bytes);
await close();
}