Python分割指定ページ数のpdfファイル方法

from PyPDF2 import PdfFileWriter, PdfFileReader

#    
start_page = 0

#    
end_page = 5

output = PdfFileWriter()
pdf_file = PdfFileReader(open("3.pdf", "rb"))
pdf_pages_len = pdf_file.getNumPages()

#   input.pdf  1-5  output.pdf
for i in range(start_page, end_page):
 output.addPage(pdf_file.getPage(i))

outputStream = open("output.pdf", "wb")
output.write(outputStream)