diff --git a/gtsam/discrete/discrete.i b/gtsam/discrete/discrete.i
index 68c2e5079..9c9869b04 100644
--- a/gtsam/discrete/discrete.i
+++ b/gtsam/discrete/discrete.i
@@ -5,20 +5,37 @@
 namespace gtsam {
 
 
-// typedef pair<size_t, size_t> DiscreteKey;
+#include<gtsam/discrete/DiscreteKey.h>
+class DiscreteKey {};
+
+class DiscreteKeys {
+  DiscreteKeys();
+  size_t size() const;
+  bool empty() const;
+  gtsam::DiscreteKey at(size_t n) const;
+  void push_back(const gtsam::DiscreteKey& point_pair);
+};
 
 #include <gtsam/discrete/DiscreteFactor.h>
 class DiscreteFactor {
 };
 
+#include <gtsam/discrete/Signature.h>
+class Signature {
+  Signature(gtsam::DiscreteKey key);
+};
+
 #include <gtsam/discrete/DecisionTreeFactor.h>
-class DecisionTreeFactor {
+class DecisionTreeFactor: gtsam::DiscreteFactor {
   DecisionTreeFactor();
 };
 
 #include <gtsam/discrete/DiscreteFactorGraph.h>
 class DiscreteFactorGraph {
   DiscreteFactorGraph();
+  void add(const gtsam::DiscreteKey& j, string table);
+  void add(const gtsam::DiscreteKeys& j, string table);
+  void print(string s = "") const;
 };
 
 }  // namespace gtsam
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 3781a16ba..d1bfc5740 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -49,6 +49,7 @@ set(ignore
     gtsam::Pose3Vector
     gtsam::KeyVector
     gtsam::BinaryMeasurementsUnit3
+    gtsam::DiscreteKey
     gtsam::KeyPairDoubleMap)
 
 set(interface_headers
diff --git a/python/gtsam/preamble/discrete.h b/python/gtsam/preamble/discrete.h
index 56a07cfdd..608508c32 100644
--- a/python/gtsam/preamble/discrete.h
+++ b/python/gtsam/preamble/discrete.h
@@ -12,3 +12,5 @@
  */
 
 #include <pybind11/stl.h>
+
+PYBIND11_MAKE_OPAQUE(gtsam::DiscreteKeys);
diff --git a/python/gtsam/specializations/discrete.h b/python/gtsam/specializations/discrete.h
index da8842eaf..447f9a4d6 100644
--- a/python/gtsam/specializations/discrete.h
+++ b/python/gtsam/specializations/discrete.h
@@ -10,3 +10,6 @@
  * with `PYBIND11_MAKE_OPAQUE` this allows the types to be modified with Python,
  * and saves one copy operation.
  */
+
+// Seems this is not a good idea with inherited stl
+//py::bind_vector<std::vector<gtsam::DiscreteKey>>(m_, "DiscreteKeys");
\ No newline at end of file
diff --git a/python/gtsam/tests/test_DiscreteFactorGraph.py b/python/gtsam/tests/test_DiscreteFactorGraph.py
index 6fad601b6..afc6630bd 100644
--- a/python/gtsam/tests/test_DiscreteFactorGraph.py
+++ b/python/gtsam/tests/test_DiscreteFactorGraph.py
@@ -31,20 +31,32 @@ from gtsam.utils.test_case import GtsamTestCase
 # using namespace std
 # using namespace gtsam
 
+from gtsam import DiscreteKeys, DiscreteFactorGraph
+
 class TestDiscreteFactorGraph(GtsamTestCase):
     """Tests for Discrete Factor Graphs."""
 
     def test_evaluation(self):
         # Three keys P1 and P2
-        P1=DiscreteKey(0,2)
-        P2=DiscreteKey(1,2)
-        P3=DiscreteKey(2,3)
+        P1 = (0, 2)
+        P2 = (1, 2)
+        P3 = (2, 3)
 
         # Create the DiscreteFactorGraph
         graph = DiscreteFactorGraph()
-#   graph.add(P1, "0.9 0.3")
-#   graph.add(P2, "0.9 0.6")
-#   graph.add(P1 & P2, "4 1 10 4")
+        graph.add(P1, "0.9 0.3")
+        graph.add(P2, "0.9 0.6")
+
+        # NOTE(fan): originally is an operator overload in C++ &
+        def discrete_and(a, b):
+            dks = DiscreteKeys()
+            dks.push_back(a)
+            dks.push_back(b)
+            return dks
+
+        graph.add(discrete_and(P1, P2), "4 1 10 4")
+
+        print(graph)
 
 #   # Instantiate Values
 #   DiscreteFactor::Values values