diff --git a/src/core_ffi/CMakeLists.txt b/src/core_ffi/CMakeLists.txt
index 95e0a87..424715e 100644
--- a/src/core_ffi/CMakeLists.txt
+++ b/src/core_ffi/CMakeLists.txt
@@ -15,6 +15,7 @@ if (KLSK_PYTHON_FFI)
         py_ffi/binder.cc
         py_ffi/codec/short_code.cc
         py_ffi/codec/common_codec.cc
+        py_ffi/py_cases.cc
     )
     target_include_directories(klotski_py PRIVATE py_ffi/include)
     target_link_libraries(klotski_py PRIVATE klotski::core)
diff --git a/src/core_ffi/py_ffi/binder.cc b/src/core_ffi/py_ffi/binder.cc
index 79492da..e04bd9f 100644
--- a/src/core_ffi/py_ffi/binder.cc
+++ b/src/core_ffi/py_ffi/binder.cc
@@ -3,9 +3,13 @@
 
 #include "py_exps.h"
 #include "py_codec.h"
+#include "py_cases.h"
 
 namespace py = pybind11;
 
+using klotski::ffi::PyCases;
+using klotski::ffi::PyCasesIter;
+
 using klotski::ffi::PyCodecExp;
 using klotski::ffi::PyShortCode;
 using klotski::ffi::PyCommonCode;
@@ -64,9 +68,35 @@ void bind_short_code(const py::module_ &m) {
         .def_static("speed_up", &PyShortCode::speed_up, py::arg("fast_mode") = false);
 }
 
+#include "group/group.h"
+#include "all_cases/all_cases.h"
+
+static PyCases group_demo() {
+    auto group_union = klotski::cases::GroupUnion::unsafe_create(169);
+    auto cases = PyCases::from(group_union.cases());
+    return cases;
+}
+
+static PyCases all_cases() {
+    return PyCases::from_ref(klotski::cases::AllCases::instance().fetch());
+}
+
 PYBIND11_MODULE(klotski, m) {
     py::register_exception<PyCodecExp>(m, "CodecExp", PyExc_ValueError);
 
+    m.def("all_cases", &all_cases);
+    m.def("group_demo", &group_demo);
+
+    py::class_<PyCases>(m, "PyCases")
+        .def("size", &PyCases::size)
+        .def("__iter__", [](const PyCases &self) {
+            return PyCasesIter(self);
+        }, py::keep_alive<0, 1>());
+
+    py::class_<PyCasesIter>(m, "PyCasesIter")
+            .def("__iter__", [](PyCasesIter &it) -> PyCasesIter& { return it; })
+            .def("__next__", &PyCasesIter::next);
+
     bind_short_code(m);
     bind_common_code(m);
 
diff --git a/src/core_ffi/py_ffi/include/py_cases.h b/src/core_ffi/py_ffi/include/py_cases.h
new file mode 100644
index 0000000..fb53bd3
--- /dev/null
+++ b/src/core_ffi/py_ffi/include/py_cases.h
@@ -0,0 +1,129 @@
+/// Klotski Engine Python FFI by Dnomd343 @2024
+
+#pragma once
+
+#include <iostream>
+
+#include <variant>
+
+#include "ranges/ranges.h"
+
+#include "py_codec.h"
+
+namespace klotski::ffi {
+
+using klotski::cases::RangesUnion;
+
+//class PyCases {
+//public:
+//    PyCases() = delete;
+//
+//    PyCases(PyCases &&cases) noexcept : real_data_(std::move(cases.real_data_)), data_(real_data_) {
+//        std::cout << "PyCases(PyCases &&) called" << std::endl;
+//        std::cout << "real_data / data_ref -> " << &real_data_ << " " << &data_ << std::endl;
+//    }
+//
+//    PyCases(const PyCases &cases) : real_data_(cases.real_data_), data_(real_data_) {
+//        std::cout << "PyCases(const PyCases &) called" << std::endl;
+//        std::cout << "real_data / data_ref -> " << &real_data_ << " " << &data_ << std::endl;
+//    }
+//
+//    PyCases& operator==(PyCases &&cases) {
+//        std::cout << "PyCases& operator==(PyCases &&) called" << std::endl;
+//        if (this != &cases) {
+//            real_data_ = std::move(cases.real_data_);
+//        }
+//        std::cout << "real_data / data_ref -> " << &real_data_ << " " << &data_ << std::endl;
+//        return *this;
+//    }
+//
+//    PyCases& operator==(const PyCases &&cases) {
+//        std::cout << "PyCases& operator==(const PyCases &&) called" << std::endl;
+//        if (this != &cases) {
+//            real_data_ = cases.real_data_;
+//        }
+//        std::cout << "real_data / data_ref -> " << &real_data_ << " " << &data_ << std::endl;
+//        return *this;
+//    }
+//
+//    [[nodiscard]] size_t size() const;
+//
+//    static PyCases from(RangesUnion &&data);
+//
+//    static PyCases from_ref(const RangesUnion &data);
+//
+//    [[nodiscard]] const RangesUnion& data_ref() const;
+//
+//private:
+//    explicit PyCases(RangesUnion &&data) : real_data_(std::move(data)), data_(real_data_) {
+//        std::cout << "PyCases init from r-value" << std::endl;
+//        std::cout << "real_data / data_ref -> " << &real_data_ << " " << &data_ << std::endl;
+//    }
+//
+//    explicit PyCases(const RangesUnion &data) : data_(data) {
+//        std::cout << "PyCases init from l-value" << std::endl;
+//    }
+//
+//    RangesUnion real_data_;
+//    const RangesUnion &data_;
+//};
+
+class PyCases {
+public:
+    using Cases = RangesUnion;
+    using CasesRef = std::reference_wrapper<const Cases>;
+
+    static PyCases from(RangesUnion &&data) {
+        return PyCases(std::move(data));
+    }
+
+    static PyCases from_ref(const RangesUnion &data) {
+        return PyCases(data);
+    }
+
+    [[nodiscard]] size_t size() const;
+
+    [[nodiscard]] const Cases& ref() const {
+
+        // if (std::holds_alternative<Cases>(data_)) {
+        //     return std::get<Cases>(data_);
+        // } else {
+        //     return std::get<CasesRef>(data_);
+        // }
+
+        return std::visit([]<typename T>(T &&arg) -> const Cases& {
+            if constexpr (std::is_same_v<std::decay_t<T>, Cases>) {
+                return arg;
+            } else {
+                return arg.get();
+            }
+        }, data_);
+    }
+
+private:
+    std::variant<Cases, CasesRef> data_;
+
+    explicit PyCases(const RangesUnion &data) : data_(std::cref(data)) {
+        std::cout << "PyCases(const RangesUnion &) called" << std::endl;
+        std::cout << "variant data index: " << data_.index() << std::endl;
+    }
+
+    explicit PyCases(RangesUnion &&data) : data_(std::move(data)) {
+        std::cout << "PyCases(RangesUnion &&) called" << std::endl;
+        std::cout << "variant data index: " << data_.index() << std::endl;
+    }
+};
+
+class PyCasesIter {
+public:
+    explicit PyCasesIter(const PyCases &data) : data_(data) {}
+
+    PyCommonCode next();
+
+private:
+    uint64_t head_ {0};
+    size_t index_ {0};
+    const PyCases &data_;
+};
+
+} // namespace klotski::ffi
diff --git a/src/core_ffi/py_ffi/py_cases.cc b/src/core_ffi/py_ffi/py_cases.cc
new file mode 100644
index 0000000..6b56ff9
--- /dev/null
+++ b/src/core_ffi/py_ffi/py_cases.cc
@@ -0,0 +1,44 @@
+#include <pybind11/pybind11.h>
+
+#include "include/py_cases.h"
+
+namespace py = pybind11;
+
+using klotski::ffi::PyCases;
+using klotski::ffi::PyCasesIter;
+using klotski::ffi::PyCommonCode;
+
+using klotski::cases::RangesUnion;
+
+size_t PyCases::size() const {
+    size_t num = 0;
+    for (const auto &x : ref()) {
+        num += x.size();
+    }
+    return num;
+}
+
+//PyCases PyCases::from(RangesUnion &&data) {
+//    return PyCases(std::move(data));
+//}
+//
+//PyCases PyCases::from_ref(const RangesUnion &data) {
+//    return PyCases(data);
+//}
+//
+//const RangesUnion& PyCases::data_ref() const {
+//    return data_;
+//}
+
+PyCommonCode PyCasesIter::next() {
+    while (head_ < 16) {
+        const auto &ranges = data_.ref()[head_];
+        if (index_ < ranges.size()) {
+            auto code = (head_ << 32) | ranges[index_++];
+            return std::bit_cast<PyCommonCode>(code);
+        }
+        ++head_;
+        index_ = 0;
+    }
+    throw py::stop_iteration();
+}