main function
void
main()
Implementation
void main() async {
List<LineStringField> lineStringFields = [];
final jsonData = await File('./linestring.json').readAsString().then((fileContents) => json.decode(fileContents));
for (var elem in jsonData) {
lineStringFields.add(LineStringField.fromJson(Map<String, dynamic>.from(elem)));
}
print(lineStringFields);
}