timer.py

#!/usr/bin/python3

import time

class TimerError(Exception):
    """A custom exception used to report errors in use of Timer class"""

class Timer:

    def __init__(self):
        self._start_time = None

    def start(self):
        """Start a new timer"""

        if self._start_time is not None:

            raise TimerError(f"Timer is running. Use .stop() to stop it")


        self._start_time = time.perf_counter()


    def stop(self):

        """Stop the timer, and report the elapsed time"""

        if self._start_time is None:

            raise TimerError(f"Timer is not running. Use .start() to start it")


        elapsed_time = time.perf_counter() - self._start_time

        self._start_time = None
    
    def getTime(self):
        return (time.perf_counter() - self._start_time)