Add fun specs.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/ht.erl b/src/ht.erl
index 749bc9e..a2f64f9 100644
--- a/src/ht.erl
+++ b/src/ht.erl
@@ -101,8 +101,11 @@ add(#history_tree{version = V, store = Store}, Entry) ->
                                      #inner{index = LeafIndex, layer = 0,
                                             hash = LeafHash})}.
 
+-spec tree_hash(history_tree()) -> binary().
 tree_hash(Tree) ->
     tree_hash(Tree, Tree#history_tree.version).
+
+-spec tree_hash(history_tree(), integer()) -> binary().
 tree_hash(_, -1) ->
     hash("");
 tree_hash(Tree, Version) ->