diff --git a/psh/commands.py b/psh/commands.py
index 164fd58..89cb0bf 100644
--- a/psh/commands.py
+++ b/psh/commands.py
@@ -1,5 +1,7 @@
 from io import StringIO
 
+from tree import TreeNode
+
 
 class BaseCommand(object):
     """Commands can be used to chain the execution of multiple programs
diff --git a/psh/example_cmd.py b/psh/example_cmd.py
index e54e408..90c496d 100644
--- a/psh/example_cmd.py
+++ b/psh/example_cmd.py
@@ -1,5 +1,7 @@
 from psh.commands import BaseCommand, register_cmd
 
+from tree import TreeNode
+
 
 @register_cmd("example")
 class Example(BaseCommand):
@@ -8,8 +10,8 @@ class Example(BaseCommand):
 
     def call(self, *args, **kwargs):
         def output_generator():
-            yield b'example'
-            yield b'command'
+            yield TreeNode(b'example')
+            yield TreeNode(b'command')
         return output_generator
 
 
@@ -26,7 +28,8 @@ class Echo(BaseCommand):
         input_generator = self.get_input_generator()
         def output_generator():
             for args in self.args:
-                yield args.encode("utf-8")
-            for line in input_generator:
-                yield line
+                yield TreeNode(args.encode("utf-8"))
+            for node in input_generator:
+                line = node.data
+                yield TreeNode(line)
         return output_generator
diff --git a/psh/formatters.py b/psh/formatters.py
index 3e50c47..436d75c 100644
--- a/psh/formatters.py
+++ b/psh/formatters.py
@@ -7,6 +7,7 @@ class Printer(BaseCommand):
 
     def call(self):
         input_generator = self.get_input_generator()
-        for line in input_generator:
+        for node in input_generator:
+            line = node.data
             print(str(line.decode('utf-8')))
         return None
diff --git a/psh/raw_commands.py b/psh/raw_commands.py
index 1d61444..d509511 100644
--- a/psh/raw_commands.py
+++ b/psh/raw_commands.py
@@ -3,6 +3,8 @@ import shlex
 from psh.formatters import Printer
 from psh.commands import BaseCommand
 
+from tree import TreeNode
+
 
 class RawCommand(BaseCommand):
     """Fallback raw command that just invokes an existing Unix utility program
@@ -20,11 +22,12 @@ class RawCommand(BaseCommand):
             p = subprocess.Popen(shlex.split(self.cmd), stdin=subprocess.PIPE, stdout=subprocess.PIPE)
             def make_output_generator():
                 input_str = b""
-                for line in input_generator:
+                for node in input_generator:
+                    line = node.data
                     input_str += line + b'\n'
                 outs, errs = p.communicate(input_str)
                 if outs:
-                    yield outs
+                    yield TreeNode(outs)
 
             return make_output_generator
         except: