isNull function
        
dynamic
isNull(
    
    
- dynamic aValue
Implementation
isNull(aValue) {
  if (aValue == null) {
    return true;
  }
  if (aValue is Map) {
    Map map = aValue;
    if (map.isEmpty) {
      return true;
    }
  }
  if (aValue is List) {
    List list = aValue;
    if (list.isEmpty) {
      return true;
    }
  }
  String sValut = aValue.toString();
  if (sValut == '' ||
      sValut == gNull ||
      sValut == "{}" ||
      sValut == "[]" ||
      sValut == '""' ||
      sValut == "\$0.00") {
    return true;
  }
  return false;
}