code: public void shrink(int count) {
          char[] keepAllocated;
  
          if (count == 0) {
              throw new IllegalArgumentException();
          }
          if (count > lastNo) {
              throw new IllegalArgumentException(count + " vs " + lastNo);
          }
          lastNo -= count;
          keepAllocated = pages[0];
          System.arraycopy(pages, count, pages, 0, lastNo + 1);
          pages[lastNo + 1] = keepAllocated;
          for (int i = lastNo + 2; i < pages.length; i++) {
              pages[i] = null;
          }
      }
docs: Remove count pages from the beginning