python splits pdf files into multiple pages

# -*- coding: utf-8 -*-
"""

"""

from PyPDF2 import PdfFileReader, PdfFileWriter 
import easygui
import os

if __name__=='__main__':
    pdf_path=easygui.fileopenbox(msg="选择要切割的PDF")
    start_page=easygui.integerbox(msg="切割开始页码（绝对页码）",upperbound=None)
    end_page=easygui.integerbox(msg="切割开始页码（绝对页码）",upperbound=None)
    print(start_page,end_page)
    pdf_input = PdfFileReader(open(pdf_path, 'rb'))
    page_count = pdf_input.getNumPages() 
    print(page_count)
    if start_page<0 or end_page>page_count:
        print("Invalid parameter.")
        exit
    pdf_output = PdfFileWriter() 
    for i in range(start_page-1,end_page):
        print(i)
        page=pdf_input.getPage(i)
        pdf_output.addPage(page) 
    pdf_output.write(open(os.path.dirname(pdf_path)+"/"+os.path.basename(pdf_path)+"_"+str(start_page)+".pdf", 'wb'))