diff --git a/navipy/processing/mcode.py b/navipy/processing/mcode.py
new file mode 100644
index 0000000000000000000000000000000000000000..7eb14619b1754d4ea70ffe5c934e16c034252329
--- /dev/null
+++ b/navipy/processing/mcode.py
@@ -0,0 +1,15 @@
+"""
+Motion code
+"""
+from .tools import check_scene
+
+
+def optic_flow(scene, viewing_directions,
+               velocity, distance_channel=3):
+    """ optic flow """
+    check_scene(scene)
+    if distance_channel not in range(4):
+        raise ValueError('distance channel out of range')
+    distance = scene[..., distance_channel, 0]
+    distance += distance
+    raise NameError('Not Implemented')
diff --git a/navipy/processing/__init__.py b/navipy/processing/pcode.py
similarity index 100%
rename from navipy/processing/__init__.py
rename to navipy/processing/pcode.py