diff --git a/libwyag.py b/libwyag.py
index d391b12..ed35388 100644
--- a/libwyag.py
+++ b/libwyag.py
@@ -460,12 +460,9 @@ argsp.add_argument("commit",
 def cmd_log(args):
     repo = repo_find()
 
-    print("digraph wyaglog{")
-    print("  node[shape=rect]")
-    log_graphviz(repo, object_find(repo, args.commit), set())
-    print("}")
+    print(log_graphviz(repo, args.commit))
 
-def log_graphviz(repo, sha, seen):
+def log_graphviz_recurse(repo, sha, seen):
     if sha in seen:
         return
     seen.add(sha)
@@ -478,7 +475,7 @@ def log_graphviz(repo, sha, seen):
 
     if "\n" in message: # keep only the first line
         message = message[:message.index("\n")]
-    print(f"  c_{sha} [label=\"{sha[0:7]}: {message}\"]")
+    yield f"  c_{sha} [label=\"{sha[0:7]}: {message}\"]"
     assert commit.fmt==b'commit'
 
     if not b'parent' in commit.kvlm.keys():
@@ -492,8 +489,20 @@ def log_graphviz(repo, sha, seen):
 
     for p in parents:
         p = p.decode("ascii")
-        print (f"  c_{sha} -> c_{p}")
-        log_graphviz(repo, p, seen)
+        yield f"  c_{sha} -> c_{p}"
+        yield from log_graphviz_recurse(repo, p, seen)
+
+def log_graphviz(repo, sha):
+    seen = set()
+
+    graph = "digraph wyaglog{\n"
+    graph += "  node[shape=rect]\n"
+    for line in log_graphviz_recurse(repo, object_find(repo, sha), seen):
+        graph += "  " + line + "\n"
+
+    graph += "}"
+
+    return graph
 
 class GitTreeLeaf (object):
     def __init__(self, mode, path, sha):