in lib/src/multipart_file_io.dart [13:21]
Future<MultipartFile> multipartFileFromPath(String field, String filePath,
{String? filename, MediaType? contentType}) async {
filename ??= p.basename(filePath);
var file = File(filePath);
var length = await file.length();
var stream = ByteStream(file.openRead());
return MultipartFile(field, stream, length,
filename: filename, contentType: contentType);
}