add method
Implementation
Future<void> add(String pathSpec) async {
pathSpec = normalizePath(pathSpec);
var index = await indexStorage.readIndex();
var stat = await fs.stat(pathSpec);
if (stat.type == FileSystemEntityType.file) {
await addFileToIndex(index, pathSpec);
} else if (stat.type == FileSystemEntityType.directory) {
await addDirectoryToIndex(index, pathSpec, recursive: true);
} else {
throw Exception('Neither file or directory');
}
await indexStorage.writeIndex(index);
}