diff --git a/README.md b/README.md
index 4b1b546..d39f16a 100644
--- a/README.md
+++ b/README.md
@@ -13,10 +13,10 @@ It also contains convenience functions to define a wider range of primitives, as
 ## Example
 
 ```
-Cube([1, 1, 2]).move([0, 0, 1])
+Cube([1, 1, 2]).move([0, 0, 1]).render()
 ```
 
-becomes
+returns
 
 
 ```
@@ -25,11 +25,29 @@ translate(v=[0, 0, 1]) { cube(size=[1, 1, 2], center=false); }
 
 ## Notable convenience functions
 
-- Usual computational geometry functions on the `Point` class that work in an arbitrary number of dimensions. Overloads for algebraic operators
+Usual computational geometry functions on the `Point` class that work in an arbitrary number of dimensions. Overloads for algebraic operators.
 
-- `Cylinder.from_ends` constructs a cylinder between two given points in space
+```
+distance = (Point((0, 0, 1)) - Point((1, 0, 1))).length()
+angle_between = Point((0, 0, 1) * 2).angle(Point((1, 0, 1)))
+```
 
-- `Polyhedron.tube` creates a tube-like or toroid polyhedron from a 2D array of points
+`Cylinder.from_ends()` constructs a cylinder between two given points in space
 
-- `PathTube` creates a tube-like or toroid polyhedron from an arbitrary path
+```
+openscad_code = Cylinder.from_ends(radius=2, p1=(0, 0, 1), p2=(1, 0, 2)).render()
+```
 
+`Polyhedron.tube()` creates a tube-like or toroid polyhedron from a 2D array of points
+
+`PathTube` creates a tube-like or toroid polyhedron from an arbitrary path
+
+```
+PathTube(
+    points=[(0,0,0), (0,0,1), (1,0,2), (1,1,0), (0,.5,0)],
+    radius=.2,
+    fn=4
+)
+```
+
+![PathTube example](https://raw.github.com/csirmaz/openscad-py/master/images/pathtube.png)
diff --git a/images/pathtube.png b/images/pathtube.png
new file mode 100644
index 0000000..f1995bf
Binary files /dev/null and b/images/pathtube.png differ
diff --git a/openscad_py.py b/openscad_py.py
index 64c3f86..1a320d4 100644
--- a/openscad_py.py
+++ b/openscad_py.py
@@ -9,14 +9,14 @@ NP_TYPE = np.float_
 
 
 class Point:
-    """Represents a point of vector in arbitrary dimensions"""
+    """Represents a point or vector in arbitrary dimensions"""
     
     def __init__(self, coords):
         self.c = np.array(coords, dtype=NP_TYPE)
         
     @classmethod
     def c(cls, coords: TUnion[list, 'Point']) -> 'Point':
-        """Ensure coords is an instance of Point"""
+        """Ensure coords is an instance of Point (idempotent)"""
         if isinstance(coords, Point):
             return coords
         return Point(coords)
@@ -177,10 +177,12 @@ class Object:
         return Difference(subject=self, tool=tool)
 
     def union(self, objects: TUnion[list, 'Object']) -> 'Object':
+        """Form the union of self and an object or list of objects"""
         return Union(child=Collection.c(objects)._add(self))
 
 
 class Header:
+    """Render a header (setting global values) of an OpensCAD file"""
     
     def __init__(self, quality: str = 'draft'):
         self.quality = quality
@@ -451,13 +453,14 @@ class Polygon(Object):
 
 
 class Collection(Object):
+    """Represents a collection of objects"""
     
     def __init__(self, coll: list):
         self.collection = coll
 
     @classmethod
     def c(cls, coll: TUnion[list, Object]) -> Object:
-        """Cast lists to collections"""
+        """Ensure the list of objects is a Collection (idempotent)"""
         if isinstance(coll, Object):
             return coll
         return cls(coll)
@@ -494,8 +497,8 @@ class Rotate(Object):
 
 class Scale(Object):
 
-    def __init__(self, v: TUnion[list, Point, float], child: Object):
-        if isinstance(v, float):
+    def __init__(self, v: TUnion[list, Point, float, int], child: Object):
+        if isinstance(v, float) or isinstance(v, int):
             v = [v, v, v]
         self.v = Point.c(v)
         self.child = child