сЭрвер.py

from urlparse import parse_qs
from datetime import datetime


def dates(environ, start_response):
    dates = parse_qs(environ['QUERY_STRING'])
    get_date = lambda d: datetime.strptime(dates[d][0], '%m/%d/%Y')
    try:
        start = get_date('start')
        end = get_date('end')
        status = '200 OK'
    except:
        status = '400 Bad Request'
    start_response(status, [('Content-Type', 'text/html')])
    return [str((end - start).days)] if status == '200 OK' else ''


if __name__ == '__main__':
    from wsgiref.simple_server import make_server
    srv = make_server('localhost', 8080, dates)
    srv.serve_forever()