# -*- coding: utf-8 -*- """ A simple fibonacci program """ import argparse parser = argparse.ArgumentParser(description='I print fibonacci sequence') parser.add_argument('-s', '--start', type=int, dest='start',                     help='Start of the sequence', required=True) parser.add_argument('-e', '--end', type=int, dest='end',                     help='End of the sequence', required=True) parser.add_argument('-v', '--verbose', action='store_true', dest='verbose',                     help='Enable debug info') import logging logger = logging.getLogger('fib') logger.setLevel(logging.DEBUG) hdr = logging.StreamHandler() formatter = logging.Formatter('[%(asctime)s] %(name)s:%(levelname)s: %(message)s') hdr.setFormatter(formatter) logger.addHandler(hdr) def infinite_fib():     a, b = 0, 1     yield a     yield b     while True:         logger.debug('Before caculation: a, b = %s, %s' % (a, b))         a, b = b, a + b         logger.debug('After caculation: a, b = %s, %s' % (a, b))         yield b def fib(start, end):     for cur in infinite_fib():         logger.debug('cur: %s, start: %s, end: %s' % (cur, start, end))         if cur > end:             return         if cur >= start:             logger.debug('Returning result %s' % cur)             yield cur def main():     args = parser.parse_args()     if args.verbose:         logger.setLevel(logging.DEBUG)     else:         logger.setLevel(logging.ERROR)     for n in fib(args.start, args.end):         print n, if __name__ == '__main__':     main()