One Line in the Log

Programs often write one line of text per event to a log.

Task: write log_line(level, *words, **fields) that builds one log line:

1. Start with level.
2. Then each of the words, each after a single space.
3. Then, for each field, | name=value — in the order the fields were passed.

With no words and no fields, the line is just the level.