docs: def findAllSingle(self, selfValue):
          '''Looks for all the single values and subclasses *recursively* and returns a list of them
  
          Args:
              selfValue: A list of single, str, int. Normally just ``self.value``
  
          Returns:
              list: A list contains only singles and subclasses.
          '''
          resultList = []
          for element in selfValue:
              if isinstance(element, Single):
                  resultList.append(element)
                  resultList += element.findAllSingle()
          return resultList