You are given a list of process log records. Each record belongs to a machine and contains a process id, the machine id, a timestamp, and an event type indicating whether the process started or ended.

For every machine, consider all of its completed processes and compute the average processing time as:

$\text{average} = \frac{\text{sum of all durations}}{\text{number of completed processes}}$

Return the result for each machine, typically ordered by machine id.

A process duration is the difference between its end timestamp and start timestamp for the same process id on the same machine.