Doc update

src/hz_format.erl

@@ -21,7 +21,7 @@
 %%% @end
 
 -module(hz_format).
--vsn("0.9.1").
+-vsn("0.9.2").
 -author("Craig Everett <ceverett@tsuriai.jp>").
 -copyright("Craig Everett <ceverett@tsuriai.jp>").
 -license("GPL-3.0-or-later").
@@ -462,9 +462,26 @@ ranks(heresy) ->
     ["k ", "m ", "b ", "t ", "q ", "e ", "z ", "y ", "r ", "Q "].
 
 
+-spec mark(Unit) -> Mark
+    when Unit :: gaju | puck,
+         Mark :: $木 | $本.
+%% @doc
+%% Retrieve the unicode codepoint for the `gaju' mark (木) or the `puck' mark (本).
+
 mark(gaju) -> $木;
 mark(puck) -> $本.
 
+
+-spec one(Unit) -> Pucks
+    when Unit  :: gaju | puck,
+         Pucks :: 1_000_000_000_000_000_000 | 1.
+%% @doc
+%% Quickly resolve the number of pucks in a given unit.
+%%
+%% The number of pucks in a gaju is so large that it can be a little bit annoying
+%% to remember the exact amount. This is a helper to simplify this when writing
+%% an app against the hakuzaru library when dealing in either unit.
+
 one(gaju) -> 1_000_000_000_000_000_000;
 one(puck) -> 1.