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.

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