Simple performance timer context manager

perf_time.py

from time import perf_counter
from datetime import timedelta

class PerfTimer:
  def __init__(self, name="Timer"):
    """ Create a performance timer context manager.
        These output the start and end of a block of code and the time it took to execute.
        They can be nested for hierarchical timing.
        
        @param name The name to output in the status messages
        
        >>> with PerfTime("MyProcess"):
        ...   import time
        ...   time.sleep(4.2)
        MyProcess: Started
        MyProcess: 0:00:0.4.213543
    """
    self.name = name

  def __enter__(self):
    self.start = perf_counter()
    print(f'{self.name}: Started')
    
  def __exit__(self, *args):
    self.end = perf_counter()
    self.interval = self.end - self.start
    print(f'{self.name}: {timedelta(seconds=self.interval)}')