formatDateTime function
Implementation
String formatDateTime(DateTime date) => '${date.year.toString()}-'
'${date.month.toString().padLeft(2, '0')}-'
'${date.day.toString().padLeft(2, '0')} '
'${date.hour.toString().padLeft(2, '0')}:'
'${date.minute.toString().padLeft(2, '0')}:'
'${date.second.toString().padLeft(2, '0')}';