diff --git a/src/base.rs b/src/base.rs
index 2e30302..0a5a4bc 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::fs;
 use std::io;
 use std::path::Path;
@@ -109,6 +109,26 @@ pub fn get_commit(oid: String) -> Commit {
     };
 }
 
+pub fn iter_commits_and_parents(mut oids: HashSet<String>) -> Vec<String> {
+    let mut visited: HashSet<String> = HashSet::new();
+    let mut oid_sequence = vec![];
+
+    while !oids.is_empty() {
+        let oid = oids.iter().next().cloned().unwrap();
+        oids.remove(&oid);
+        if oid == "" || visited.contains(&oid) {
+            continue;
+        }
+        visited.insert(oid.clone());
+        oid_sequence.push(oid.clone());
+
+        let commit = get_commit(oid);
+        oids.insert(commit.parent);
+    }
+
+    return oid_sequence;
+}
+
 pub fn checkout(oid: String) {
     let commit = get_commit(oid.clone());
     read_tree(commit.tree);
diff --git a/src/main.rs b/src/main.rs
index bddb738..8115870 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,4 +1,5 @@
 use clap::{App, Arg, ArgMatches, SubCommand};
+use std::collections::HashSet;
 use std::fs;
 mod base;
 mod data;
@@ -152,7 +153,18 @@ fn tag(matches: ArgMatches) {
 }
 
 fn k() {
+    let mut oids = HashSet::new();
     for refinfo in data::iter_refs() {
         println!("{} {}", refinfo.0, refinfo.1);
+        oids.insert(refinfo.1);
     }
+
+    for oid in base::iter_commits_and_parents(oids) {
+        let commit = base::get_commit(oid.clone());
+        println!("{}", oid);
+        if commit.parent != "" {
+            println!("Parent: {}", commit.parent);
+        }
+    }
+    // TODO visualize refs
 }