diff --git a/Homework4/src/pypart.cc b/Homework4/src/pypart.cc
index b56c6d0..ddfa803 100644
--- a/Homework4/src/pypart.cc
+++ b/Homework4/src/pypart.cc
@@ -1,52 +1,68 @@
 #include <functional>
 #include <iostream>
 #include <pybind11/pybind11.h>
 
 #include "system_evolution.hh"
 #include "particles_factory_interface.hh"
 #include "csv_writer.hh"
 #include "compute.hh"
 #include "compute_temperature.hh"
 #include "material_points_factory.hh"
 #include "ping_pong_balls_factory.hh"
 #include "planets_factory.hh"
 
 namespace py = pybind11;
 
 PYBIND11_MODULE(pypart, m) {
     m.doc() = "Python binding for the particles code.";
     
+    
     // Class System
     py::class_<System>(m, "System");
     
+    
     // Class SystemEvolution
     py::class_<SystemEvolution, std::unique_ptr<SystemEvolution>>(m, "SystemEvolution",
                                                                   py::dynamic_attr())
         .def(py::init([](std::unique_ptr<System>()){return std::unique_ptr<SystemEvolution>();}),
              py::return_value_policy::move)
         .def("evolve",      &SystemEvolution::evolve)
         .def("addCompute",  &SystemEvolution::addCompute)
         .def("getSystem",   &SystemEvolution::getSystem, py::return_value_policy::reference)
         .def("setNSteps",   &SystemEvolution::setNSteps)
         .def("setDumpFreq", &SystemEvolution::setDumpFreq);
     
+    
     // Class ParticlesFactoryInterface
     py::class_<ParticlesFactoryInterface>(m, "ParticlesFactoryInterface",
                                           py::dynamic_attr())
         .def_static("getInstance", &ParticlesFactoryInterface::getInstance,
                     py::return_value_policy::reference)
         .def("getSystemEvolution", &ParticlesFactoryInterface::getSystemEvolution,
              py::return_value_policy::reference)
         .def_property_readonly("system_evolution",&ParticlesFactoryInterface::getSystemEvolution);
     
+    
     // Class MaterialPointsFactory
     py::class_<MaterialPointsFactory, ParticlesFactoryInterface,
         std::shared_ptr<MaterialPointsFactory>>(m, "MaterialPointsFactory")
     
         .def("getInstance", &MaterialPointsFactory::getInstance,
              py::return_value_policy::reference)
         .def("createSimulation",
              py::overload_cast<const std::string &, Real, py::function>(
                  &MaterialPointsFactory::createSimulation<py::function>),
              py::return_value_policy::reference);
+    
+    
+    // Class PlanetsFactory
+    py::class_<PlanetsFactory, ParticlesFactoryInterface,
+        std::shared_ptr<PlanetsFactory>>(m, "PlanetsFactory")
+    
+        .def("getInstance", &PlanetsFactory::getInstance,
+             py::return_value_policy::reference)
+        .def("createSimulation",
+             py::overload_cast<const std::string &, Real, bool>(
+                 &ParticlesFactoryInterface::createSimulation),
+             py::return_value_policy::reference);
 }