Adopt Access behaviours to Geef.Object instead of implementing the deprecated Access protocol

lib/geef/object.ex

@@ -1,6 +1,10 @@
 require Record
 
 defmodule Geef.Object do
+  @behaviour Access
+  alias Geef.Object
+  alias Geef.Tree
+
   defstruct type: nil, id: nil, handle: nil
 
   def lookup(repo, id) do
@@ -32,4 +36,24 @@ defmodule Geef.Object do
     end
   end
 
+  def fetch(tree = %Object{type: :tree}, key) when is_number(key) do
+    Tree.nth(tree, key)
+  end
+
+  def fetch(tree = %Object{type: :tree}, key) do
+    Tree.get(tree, key)
+  end
+
+  def get(tree = %Object{type: :tree}, key) do
+    case fetch(tree, key) do
+      {:ok, entry} -> entry
+      {:error, _} -> nil
+    end
+  end
+
+  # Git data is immutable
+  def get_and_update(_tree, _key, _fun) do
+    raise ArgumentError
+  end
+
 end

lib/geef/tree.ex

@@ -33,31 +33,6 @@ defmodule Geef.Tree do
 
 end
 
-defimpl Access, for: Geef.Object do
-  alias Geef.Object
-  alias Geef.Tree
-
-  def get(tree = %Object{type: :tree}, key) when is_number(key) do
-    case Tree.nth(tree, key) do
-      {:ok, entry} -> entry
-      {:error, _} -> nil
-    end
-  end
-
-  def get(tree = %Object{type: :tree}, key) do
-    case Tree.get(tree, key) do
-      {:ok, entry} -> entry
-      {:error, _} -> nil
-    end
-  end
-
-  # Git data is immutable
-  def get_and_update(_tree, _key, _fun) do
-    raise ArgumentError
-  end
-
-end
-
 defmodule Geef.TreeError do
   defexception [reason: nil]