Timer context manager

timer.py

import time

class Timer:
    def __init__(self, times):
        self.times = times
        self.start = None
        
    def __enter__(self):
        self.start = time.perf_counter()
        return self.start
    
    def __exit__(self, exc_type, exc_val, exc_tb):
        finish = time.perf_counter()
        self.times.append((self.start, finish))
        return False