For each path we determine the list of formatters that are interested in formatting it. From there, we sort
the list of formatters first by priority (lower value, higher priority) and then by name (lexicographically).
With this information we create a batch key which is based on the unique sequence of formatters. When enough paths with the same sequence is ready we apply them in order to each formatter.
By default, with no special configuration, this model guarantees that a given path will only be processed by one formatter at a time.
If a user wishes to influence the order in which formatters are applied they can use the priority field.
Signed-off-by: Brian McGee <brian@bmcgee.ie>
