import time

def performance(unit):

    def log_perf(f):

        def perf(*args,**kw):

            print '[%s]%s()...'%(unit,f.__name__)

            return f(*args,**kw)

        return perf

    return log_perf

@performance('msdfas')

def factorial(n):

    return reduce(lambda x,y: x*y, range(1, n+1))

print factorial(10)