App::Pebble::Helpers::DateTime::Duration - DateTime::Duration helpers.
Support DateTime::Duration "natively" by making sure they TO_JSON-ify properly, and provide some useful extra helper methods.
Return a formatted (in $format) string of the duration, using DateTime::Format::Duration. Refer to that module for formatting options.
Default: duration in seconds.
Return a human-readable string, e.g. "8h, 2m, 24s".