tags
List the unique tag names used in the journal. With a TAGREGEX argument,
only tag names matching the regular expression (case insensitive) are
shown. With QUERY arguments, only transactions matching the query are
considered.

With the --values flag, the tags' unique values are listed instead.

With --parsed flag, all tags or values are shown in the order they are
parsed from the input data, including duplicates.

With -E/--empty, any blank/empty values will also be shown, otherwise
they are omitted.

_FLAGS
