expose getNativeCode to python

Signed-off-by: Thien Nguyen <nguyentm@ornl.gov>

python/examples/ibm_get_native_code.py

+import xacc
+xacc.qasm('''
+.compiler xasm
+.circuit iterative_qpe
+.qbit q
+H(q[0]);
+X(q[1]);
+// Prepare the state:
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+H(q[0]);
+// Measure and reset
+Measure(q[0], c[0]);
+Reset(q[0]);
+H(q[0]);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+// Conditional rotation
+if(c[0]) {
+    Rz(q[0], -pi/2);
+}
+H(q[0]);
+Measure(q[0], c[1]);
+Reset(q[0]);
+H(q[0]);
+CPhase(q[0], q[1], -5*pi/8);
+CPhase(q[0], q[1], -5*pi/8);
+if(c[0]) {
+    Rz(q[0], -pi/4);
+}
+if(c[1]) {
+    Rz(q[0], -pi/2);
+}
+H(q[0]);
+Measure(q[0], c[2]);
+Reset(q[0]);
+H(q[0]);
+CPhase(q[0], q[1], -5*pi/8);
+if(c[0]) {
+    Rz(q[0], -pi/8);
+}
+if(c[1]) {
+    Rz(q[0], -pi/4);
+}
+if(c[2]) {
+    Rz(q[0], -pi/2);
+}
+H(q[0]);
+Measure(q[0], c[3]);
+''')
+
+f = xacc.getCompiled('iterative_qpe')
+
+qpu = xacc.getAccelerator('ibm:ibmq_manhattan')
+print('HOWDY:\n', qpu.getNativeCode(f))
\ No newline at end of file

python/py_accelerator.cpp

@@ -112,6 +112,12 @@ void bind_accelerator(py::module &m) {
                xacc::Accelerator::updateConfiguration,
            "")
       .def("getConnectivity", &xacc::Accelerator::getConnectivity, "")
+      .def(
+          "getNativeCode",
+          [](xacc::Accelerator &qpu, std::shared_ptr<CompositeInstruction> f) {
+            return qpu.getNativeCode(f);
+          },
+          "")
       .def("configurationKeys", &xacc::Accelerator::configurationKeys, "")
       .def("contributeInstructions", &xacc::Accelerator::contributeInstructions,
            "");