def checkPresenceOfFiles(filenames):

    missing = []
    for filename in filenames:
        if not os.path.exists(filename):
            missing.append(filename)
    return missing
Decorator to make a view only accept particular request methods.  Usage::
dataset/ETHPy150Open CGATOxford/cgat/CGAT/IOTools.py/checkPresenceOfFiles--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.2/django/views/decorators/http.py/require_http_methods