docs: def toc():
      """toc() -> float | None
  
      Returns the total elapsed seconds since the most recent tic(), or
      None if tic() was not called.
  
      Examples:
  
      >>> import time
  
      >>> tic()
      >>> time.sleep(1.2)
      >>> elapsed = toc()
  
      >>> assert abs(elapsed - 1.2) <= 1e-2
  
      .. note:: The tic() and toc() functions are simplistic and may introduce
              significant overhead, especially in tight loops.  Their use should
              be limited to one-off experiments and rough numbers.  The Python
              profile package (i.e. 'import profile') should be used for serious
              and detailed profiling.
      """
      end = datetime.datetime.now()
      return totalSeconds( end - TICs.pop() ) if len(TICs) else None