python decorator usage example

timer.py

import time
import functools
def timer(func):
"""print the runtime of the decorated function"""
    functools.wraps(func)
    def timer_wraper(*args,**kargs):
        #get time before call func
        start_time = time.perf_counter()
        #call func
        value = func(*args,**kargs)
        #get time after call func
        end_time = time.perf_counter()
        #calculate run time
        run_time = end_time - start_time
        print(f'Finished {func.__name__!r} in {run_time:.4f} secs')
        return value
    return timer_wraper
    
#usage example
@timer
def waste_some_time(num_time):
    for _ in range(num_time):
        sum([i**2 for i in range(10000)])
waste_some_time(100)