# Filename : example.py
# Copyright : 2020 By Bianchenghao6
# Author by : bianchenghao6.com
# Date : 2020-08-22
class ReportFormat(object):
     PDF = 0
     TEXT = 1
 class Report(object):
     def __init__(self, format_):
         self.title = 'Monthly report'
         self.text = ['Things are going', 'really, really well.']
         self.format_ = format_
 class Handler(object):
     def __init__(self):
         self.nextHandler = None
     def handle(self, request):
         self.nextHandler.handle(request)
 class PDFHandler(Handler):
     def handle(self, request):
         if request.format_ == ReportFormat.PDF:
             self.output_report(request.title, request.text)
         else:
             super(PDFHandler, self).handle(request)
     def output_report(self, title, text):
         print('')
         print(' ')
         print(' ' % title)
         print(' ')
         print(' ')
         for line in text:
             print(' 
%s' % line)
         print(' ')
         print(' ')
 class TextHandler(Handler):
     def handle(self, request):
         if request.format_ == ReportFormat.TEXT:
             self.output_report(request.title, request.text)
         else:
             super(TextHandler, self).handle(request)
     def output_report(self, title, text):
         print(5*'*' + title + 5*'*')
         for line in text:
             print(line)
 class ErrorHandler(Handler):
     def handle(self, request):
         print("Invalid request")
 if __name__ == '__main__':
     report = Report(ReportFormat.TEXT)
     pdf_handler = PDFHandler()
     text_handler = TextHandler()
     pdf_handler.nextHandler = text_handler
     text_handler.nextHandler = ErrorHandler()
     pdf_handler.handle(report)
 

Things are going 

 really, really well.