addAssets function
Implementation
void addAssets(Map<AssetId, dynamic> assets, InMemoryAssetWriter writer) {
assets.forEach((id, value) {
if (value is String) {
writer.assets[id] = utf8.encode(value);
} else if (value is List<int>) {
writer.assets[id] = value;
} else {
throw ArgumentError(
'`assets` values must be of type `String` or `List<int>`, got '
'${value.runtimeType}.');
}
});
}