docs: def to_json(self):
          """
          Returns:
              str:
          """
          data = dict()
  
          for key, value in self.__dict__.items():
              if value:
                  if hasattr(value, 'to_dict'):
                      data[key] = value.to_dict()
                  elif isinstance(value, datetime):
                      data[key] = value.strftime('%Y-%m-%d %H:%M:%S')
                  else:
                      data[key] = value
  
          return json.dumps(data)