diff --git a/MVMCoreUI/Atomic/Protocols/ModelProtocols/MoleculeModelProtocol.swift b/MVMCoreUI/Atomic/Protocols/ModelProtocols/MoleculeModelProtocol.swift
index f7927a1b..4b432c2e 100644
--- a/MVMCoreUI/Atomic/Protocols/ModelProtocols/MoleculeModelProtocol.swift
+++ b/MVMCoreUI/Atomic/Protocols/ModelProtocols/MoleculeModelProtocol.swift
@@ -24,28 +24,28 @@ public extension MoleculeModelProtocol {
 public extension MoleculeModelProtocol {
     
     // Base case. No additional children to traverse.
-    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol)->Result) -> Result {
-        return nextPartialResult(initialResult, self)
+    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, depth: Int, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol, Int)->Result) -> Result {
+        return nextPartialResult(initialResult, self, depth)
     }
     
     // Base case. No additional children to traverse.
-    func depthFirstTraverse(options: TreeTraversalOptions, onVisit: (MoleculeModelProtocol)->Void) {
-        onVisit(self)
+    func depthFirstTraverse(options: TreeTraversalOptions, depth: Int, onVisit: (Int, MoleculeModelProtocol)->Void) {
+        onVisit(depth, self)
     }
     
 }
 
 public extension Array where Element == MoleculeModelProtocol {
     
-    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol)->Result) -> Result {
+    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, depth: Int, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol, Int)->Result) -> Result {
         return reduce(initialResult) { (result, molecule) -> Result in
-            return molecule.reduceDepthFirstTraverse(options: options, initialResult: result, nextPartialResult: nextPartialResult)
+            return molecule.reduceDepthFirstTraverse(options: options, depth: depth, initialResult: result, nextPartialResult: nextPartialResult)
         }
     }
     
-    func depthFirstTraverse(options: TreeTraversalOptions, callback: (MoleculeModelProtocol)->Void) {
+    func depthFirstTraverse(options: TreeTraversalOptions, depth: Int, callback: (Int, MoleculeModelProtocol)->Void) {
         forEach { (molecule) in
-            molecule.depthFirstTraverse(options: options, onVisit: callback)
+            molecule.depthFirstTraverse(options: options, depth: depth, onVisit: callback)
         }
     }
 }
diff --git a/MVMCoreUI/Atomic/Protocols/ModelProtocols/ParentMoleculeModelProtocol.swift b/MVMCoreUI/Atomic/Protocols/ModelProtocols/ParentMoleculeModelProtocol.swift
index a1d9d225..2ec05db4 100644
--- a/MVMCoreUI/Atomic/Protocols/ModelProtocols/ParentMoleculeModelProtocol.swift
+++ b/MVMCoreUI/Atomic/Protocols/ModelProtocols/ParentMoleculeModelProtocol.swift
@@ -16,38 +16,39 @@ public protocol ParentMoleculeModelProtocol: MoleculeModelProtocol {
 
 public extension ParentMoleculeModelProtocol {
     
-    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol) -> Result) -> Result {
+    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, depth: Int, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol, Int) -> Result) -> Result {
         var result = initialResult
         if (options == .parentFirst) {
-            result = nextPartialResult(result, self)
+            result = nextPartialResult(result, self, depth)
         }
         result = children.reduce(result) { (result, molecule) -> Result in
             if let additionalParent = molecule as? ParentMoleculeModelProtocol {
                 // Safety net to make sure the ParentMoleculeModelProtocol's method extension is called over the base MoleculeModelProtocol.
-                return additionalParent.reduceDepthFirstTraverse(options: options, initialResult: result, nextPartialResult: nextPartialResult)
+                return additionalParent.reduceDepthFirstTraverse(options: options, depth: depth + 1, initialResult: result, nextPartialResult: nextPartialResult)
             }
-            return molecule.reduceDepthFirstTraverse(options: options, initialResult: result, nextPartialResult: nextPartialResult)
+            return molecule.reduceDepthFirstTraverse(options: options, depth: depth + 1, initialResult: result, nextPartialResult: nextPartialResult)
         }
         if (options == .childFirst) {
-            result = nextPartialResult(result, self)
+            result = nextPartialResult(result, self, depth)
         }
         // if options == .leafOnly don't call on self.
         return result
     }
     
-    func depthFirstTraverse(options: TreeTraversalOptions, onVisit: (MoleculeModelProtocol)->Void) {
+    func depthFirstTraverse(options: TreeTraversalOptions, depth: Int, onVisit: (Int, MoleculeModelProtocol)->Void) {
         if (options == .parentFirst) {
-            onVisit(self)
+            onVisit(depth, self)
         }
         children.forEach { (molecule) in
             if let additionalParent = molecule as? ParentMoleculeModelProtocol {
                 // Safety net to make sure the ParentMoleculeModelProtocol's method extension is called over the base MoleculeModelProtocol.
-                additionalParent.depthFirstTraverse(options: options, onVisit: onVisit)
+                additionalParent.depthFirstTraverse(options: options, depth: depth + 1, onVisit: onVisit)
+            } else {
+                molecule.depthFirstTraverse(options: options, depth: depth + 1, onVisit: onVisit)
             }
-            molecule.depthFirstTraverse(options: options, onVisit: onVisit)
         }
         if (options == .childFirst) {
-            onVisit(self)
+            onVisit(depth, self)
         }
         // if options == .leafOnly don't call on self.
     }
diff --git a/MVMCoreUI/Atomic/Protocols/MoleculeTreeTraversalProtocol.swift b/MVMCoreUI/Atomic/Protocols/MoleculeTreeTraversalProtocol.swift
index 137d8a77..4e7efabb 100644
--- a/MVMCoreUI/Atomic/Protocols/MoleculeTreeTraversalProtocol.swift
+++ b/MVMCoreUI/Atomic/Protocols/MoleculeTreeTraversalProtocol.swift
@@ -17,9 +17,9 @@ public protocol MoleculeTreeTraversalProtocol {
         
     // Future options -- Parent first depth first, leaves only.
     
-    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol)->Result) -> Result
+    func reduceDepthFirstTraverse<Result>(options: TreeTraversalOptions, depth: Int, initialResult: Result, nextPartialResult: (Result, MoleculeModelProtocol, Int)->Result) -> Result
     
-    func depthFirstTraverse(options: TreeTraversalOptions, onVisit: (MoleculeModelProtocol)->Void)
+    func depthFirstTraverse(options: TreeTraversalOptions, depth: Int, onVisit: (Int, MoleculeModelProtocol)->Void)
     
     //func breadthFirstTraverse()
 }
@@ -31,19 +31,19 @@ public protocol MoleculeTreeTraversalProtocol {
 extension MoleculeTreeTraversalProtocol {
     
     func countMolecules(options: TreeTraversalOptions = .parentFirst) -> Int {
-        return reduceDepthFirstTraverse(options: options, initialResult: 0) { (accumulator, molecule) in
+        return reduceDepthFirstTraverse(options: options, depth: 0, initialResult: 0) { (accumulator, molecule, depth) in
             return accumulator + 1
         }
     }
     
     func printMolecules(options: TreeTraversalOptions = .parentFirst) {
-        depthFirstTraverse(options: options) { (molecule) in
-            print("\"\(molecule.moleculeName)\" [\(molecule)]")
+        depthFirstTraverse(options: options, depth: 1) { (depth, molecule) in
+            print("\(String(repeating: ">>", count: depth)) \"\(molecule.moleculeName)\" [\(molecule)]")
         }
     }
     
     func allMoleculesOfType<T>(options: TreeTraversalOptions = .parentFirst) -> [T] {
-        return reduceDepthFirstTraverse(options: options, initialResult: []) { (accumulator, molecule) in
+        return reduceDepthFirstTraverse(options: options, depth: 0, initialResult: []) { (accumulator, molecule, depth) in
             if let typedMolecule = molecule as? T {
                 return accumulator + [typedMolecule]
             }