code: func NewLFUNoTS(size int) Cache {
  	if size < 1 {
  		panic("invalid cache size")
  	}
  
  	return &LFUNoTS{
  		frequencyList: list.New(),
  		cache:         NewMemoryNoTS(),
  		size:          size,
  		currentSize:   0,
  	}
  }
docs: // NewLFUNoTS creates a new LFU cache struct for further cache operations. Size
  // is used for limiting the upper bound of the cache