diff --git a/source/niknaks/containers.d b/source/niknaks/containers.d
index dd255bc..6f36008 100644
--- a/source/niknaks/containers.d
+++ b/source/niknaks/containers.d
@@ -589,4 +589,342 @@ unittest
 
     // Destroy the map (such that it ends the sweeper
     destroy(map);
+}
+
+// Given [0, 1, 5]
+// and shift right at index 1
+// then 0 moves into 1's place
+// 0's position is then filled with T.init
+
+public T[] shift(T)(T[] array, size_t position, bool rightwards = false, bool shrink = false)
+{
+    // Out of range
+    if(position >= array.length)
+    {
+        return array;
+    }
+
+    // if rightwards
+    if(rightwards)
+    {
+        // nothing further left than index 0
+        if(!position)
+        {
+            return array;
+        }
+
+        for(size_t i = position; i > 0; i--)
+        {
+            array[i] = array[i-1];
+        }
+
+        // no shrink, then fill with T.init
+        if(!shrink)
+        {
+            array[0] = T.init;
+        }
+        // chomp left-hand side
+        else
+        {
+            array = array[1..$];
+        }
+    }
+    
+    return array;
+}
+
+// rightwards testung (no shrink)
+unittest
+{
+    int[] numbas = [1, 5, 2];
+    numbas = numbas.shift(1, true);
+
+    // should now be [0, 1, 2]
+    writeln(numbas);
+    assert(numbas == [0, 1, 2]);
+
+    numbas = [1, 5, 2];
+    numbas = numbas.shift(0, true);
+
+    // should now be [1, 5, 2]
+    writeln(numbas);
+    assert(numbas == [1, 5, 2]);
+    
+    numbas = [1, 5, 2];
+    numbas = numbas.shift(2, true);
+
+    // should now be [0, 1, 5]
+    writeln(numbas);
+    assert(numbas == [0, 1, 5]);
+
+    numbas = [1, 2];
+    numbas = numbas.shift(1, true);
+
+    // should now be [0, 1]
+    writeln(numbas);
+    assert(numbas == [0, 1]);
+
+    numbas = [1, 2];
+    numbas = numbas.shift(0, true);
+
+    // should now be [1, 2]
+    writeln(numbas);
+    assert(numbas == [1, 2]);
+
+    numbas = [];
+    numbas = numbas.shift(0, true);
+
+    // should now be []
+    writeln(numbas);
+    assert(numbas == []);
+}
+
+public T[] remove(T)(T[] array, size_t idx)
+{
+    // Return your array on this
+    if(!(idx < array.length))
+    {
+        return array;
+    }
+
+    return null;
+}
+
+// TODO: make delegate kak
+// public interface InclusionStratergy(T)
+// {
+//     public bool include(T item);
+// }
+
+// private class AlwaysStrat(T) : InclusionStratergy
+// {
+//     public override bool include(T item)
+//     {
+//         return true;
+//     }
+// }
+
+public template Always(T)
+{
+    public bool Always(Tree!(T) treeNode)
+    {
+        version(unittest)
+        {
+            import std.stdio : writeln;
+            writeln("Strat for: ", treeNode);
+        }
+        return true;
+    }
+}
+
+public template Nothing(T)
+{
+    public void Nothing(Tree!(T) treeNode)
+    {
+
+    }
+}
+
+public template InclusionStratergy(T)
+{
+    public alias InclusionStratergy = bool delegate(Tree!(T) item);
+}
+
+// Called prior to visitation?
+public template TouchStratergy(T)
+{
+    public alias TouchStratergy = void delegate(Tree!(T) item);
+}
+
+import std.string : format;
+
+// TODO: Technically this is a graph
+public class Tree(T)
+{
+    private T value;
+    private Tree!(T)[] children;
+
+    this(T value)
+    {
+        this.value = value;
+    }
+
+    this()
+    {
+
+    }
+
+    public void setValue(T value)
+    {
+        this.value = value;
+    }
+
+    public void appendNode(Tree!(T) node)
+    {
+        this.children ~= node;
+    }
+
+    public bool removeNode(Tree!(T) node)
+    {
+        bool found = false;
+        for(size_t i = 0; i < this.children.length; i++)
+        {
+            found = this.children[i] == node;
+            if(found)
+            {
+                
+            }
+        }
+
+        return true;
+    }
+
+    public T[] dfs
+    (
+        InclusionStratergy!(T) strat = toDelegate(&Always!(T)),
+        TouchStratergy!(T) touch = toDelegate(&Nothing!(T))
+    )
+    {
+        version(unittest)
+        {
+            writeln("dfs entry: ", this);
+        }
+        
+        T[] collected;
+        scope(exit)
+        {
+            version(unittest)
+            {
+                writeln("leaving node ", this, " with collected ", collected);
+            }
+        }
+
+        // Touch
+        touch(this); // root[x]
+
+        foreach(Tree!(T) child; this.children) // subtree[x], 
+        {
+            if(strat(child))
+            {
+                version(unittest)
+                {
+                    writeln("dfs, strat good for child: ", child);
+                }
+
+                // Visit
+                collected ~= child.dfs(strat, touch);
+            }
+            else
+            {
+                version(unittest)
+                {
+                    writeln("dfs, strat ignored for child: ", child);
+                }
+            }
+        }
+
+        // "Visit"
+        collected ~= this.value;
+        
+        
+        return collected;
+    }
+
+    public override string toString()
+    {
+        return format("TreeNode [val: %s]", this.value);
+    }
+}
+
+
+version(unittest)
+{
+    import std.functional : toDelegate;
+    import std.stdio : writeln;
+
+    private void DebugTouch(T)(Tree!(T) node)
+    {
+        writeln("Touching tree node ", node);
+    }
+}
+
+unittest
+{
+    Tree!(string) treeOfStrings = new Tree!(string)("Top");
+
+    Tree!(string) subtree_1 = new Tree!(string)("1");
+    Tree!(string) subtree_2 = new Tree!(string)("2");
+    Tree!(string) subtree_3 = new Tree!(string)("3");
+
+    treeOfStrings.appendNode(subtree_1);
+    treeOfStrings.appendNode(subtree_2);
+    treeOfStrings.appendNode(subtree_3);
+
+
+    InclusionStratergy!(string) strat = toDelegate(&Always!(string));
+    TouchStratergy!(string) touch = toDelegate(&DebugTouch!(string));
+
+    string[] result = treeOfStrings.dfs(strat, touch);
+    writeln("dfs: ", result);
+
+    assert(result[0] == "1");
+    assert(result[1] == "2");
+    assert(result[2] == "3");
+    assert(result[3] == "Top");
+}
+
+public class VisitationTree(T) : Tree!(T)
+{
+    private bool visisted;    
+
+    this(T value)
+    {
+        super(value);
+    }
+
+    public T[] linearize()
+    {
+        return dfs(toDelegate(&_shouldVisit), toDelegate(&_touch));
+    }
+
+    private static bool _shouldVisit(Tree!(T) tnode)
+    {
+        VisitationTree!(T) vnode = cast(VisitationTree!(T))tnode;
+        return vnode && !vnode.isVisited();
+    }
+
+    private static void _touch(Tree!(T) tnode)
+    {
+        VisitationTree!(T) vnode = cast(VisitationTree!(T))tnode;
+        if(vnode)
+        {
+            vnode.mark();
+        }
+    }
+
+    private void mark()
+    {
+        this.visisted = true;
+    }
+    
+    private bool isVisited()
+    {
+        return this.visisted;
+    }
+}
+
+unittest
+{
+    VisitationTree!(string) root = new VisitationTree!(string)("root");
+
+    VisitationTree!(string) thing = new VisitationTree!(string)("subtree");
+    root.appendNode(thing);
+    thing.appendNode(root);
+
+    string[] linearized = root.linearize();
+    writeln(linearized);
+
+    assert(linearized[0] == "subtree");
+    assert(linearized[1] == "root");
+
 }
\ No newline at end of file