code: def _shrink_list(self, shrink):
          
          res = []
  
          if len(shrink) == 1:
              return self.shrink(shrink[0])
          else:
              for a in shrink:
                  temp = self.shrink(a)
  
                  if temp:
                      res.append(temp)
          return res
docs: Shrink list down to essentials
  
          :param shrink: List to shrink
          :type shrink: list
          :return: Shrunk list
          :rtype: list