diff --git a/marketsim/gen/_out/_types.py b/marketsim/gen/_out/_types.py
new file mode 100644
index 00000000..c1f3bed6
--- /dev/null
+++ b/marketsim/gen/_out/_types.py
@@ -0,0 +1,25 @@
+#class ITrader(object): pass
+#class IGraph(object): pass
+#class CandleStick(object): pass
+#class Volume(object,Int): pass
+#class IAccount(object): pass
+#class Side(object): pass
+#class Boolean(object): pass
+#class Price(object,Float): pass
+#class IOrderQueue(object): pass
+#class Float(object): pass
+#class Int(object,Float): pass
+#class ILink(object): pass
+#class IOrderBook(object): pass
+#class IEvent(object): pass
+#class IMultiAssetStrategy(object): pass
+#class ITwoWayLink(object): pass
+#class ISingleAssetStrategy(object): pass
+#class ISingleAssetTrader(object,IAccount,ITrader): pass
+#class IVolumeLevels(object): pass
+#class Order(object): pass
+#class IDifferentiable(object,IFunction[Float]): pass
+#class ITimeSerie(object): pass
+#class Any(object): pass
+#IOrderGenerator = IObservable[Order]
+#class String(object): pass
diff --git a/marketsim/gen/_out/trash/types/_types.py b/marketsim/gen/_out/trash/types/_types.py
new file mode 100644
index 00000000..f950ffdb
--- /dev/null
+++ b/marketsim/gen/_out/trash/types/_types.py
@@ -0,0 +1,4 @@
+#class T(object): pass
+#class R(object,T): pass
+#T1 = T
+#class U(object,T,R): pass
diff --git a/marketsim/gen/src/main/scala/generator/python/gen.scala b/marketsim/gen/src/main/scala/generator/python/gen.scala
index 052fb420..a7340bea 100644
--- a/marketsim/gen/src/main/scala/generator/python/gen.scala
+++ b/marketsim/gen/src/main/scala/generator/python/gen.scala
@@ -68,6 +68,25 @@ package object gen
                 }
             }
 
+            if (p.types.nonEmpty)
+            {
+                for (out <- managed(printWriter(dir, "_types.py")))
+                {
+                    p.types.values foreach {
+                        case interface : Typed.InterfaceDecl =>
+                            if (interface.generics.isEmpty) {
+                                val name = interface.name
+                                val bases = interface.bases map { "," + _.toString } mkString ""
+                                out.println(s"#class $name(object$bases): pass")
+                            }
+
+                        case alias : Typed.AliasDecl =>
+                            if (alias.generics.isEmpty)
+                                out.println("#" + alias.name + " = " + alias.target.toString)
+                    }
+                }
+            }
+
             p.functionAliases.values foreach { f =>
                 generationUnit(f.target) map { g =>
                     idx_out.println(base.withImports(Printer.importsOf(f.target).as(f.name)))