substitute the result for RFC1123_DATE. call the function re.compile with an argument raw string '^\w{6,9}, %s-%s-%s %s GMT$' formated with __D, __M, __Y2 and __T,
RFC850_DATE = re . compile ( r'^\w{6,9}, %s-%s-%s %s GMT$' % ( __D , __M , __Y2 , __T ) )