diff --git a/src/core_ffi/python_ffi/CMakeLists.txt b/src/core_ffi/python_ffi/CMakeLists.txt
index c609e94..5df5d96 100644
--- a/src/core_ffi/python_ffi/CMakeLists.txt
+++ b/src/core_ffi/python_ffi/CMakeLists.txt
@@ -6,9 +6,8 @@ set(CMAKE_CXX_STANDARD 23)
 set(KLSK_PYTHON_FFI_SRC
     klotski.cc
 
-    binder/cases.cc
-    binder/common_code.cc
-    binder/short_code.cc
+    binder/klsk_cases.cc
+    binder/klsk_code.cc
     binder/group_union.cc
     binder/group.cc
     binder/fast_cal.cc
diff --git a/src/core_ffi/python_ffi/binder/common_code.cc b/src/core_ffi/python_ffi/binder/common_code.cc
deleted file mode 100644
index 82ab88b..0000000
--- a/src/core_ffi/python_ffi/binder/common_code.cc
+++ /dev/null
@@ -1,32 +0,0 @@
-#include "binder.h"
-
-void bind_common_code(const py::module_ &m) {
-    py::class_<PyCommonCode>(m, "CommonCode")
-        .def(py::init<uint64_t>())
-        .def(py::init<PyShortCode>())
-        .def(py::init<std::string_view>())
-
-        .def(py::hash(py::self))
-        .def("__str__", &PyCommonCode::str)
-        .def("__int__", &PyCommonCode::value)
-        .def("__repr__", &PyCommonCode::repr)
-
-        .def(py::self == py::self)
-        .def(py::self < py::self).def(py::self <= py::self)
-        .def(py::self > py::self).def(py::self >= py::self)
-
-        .def(py::self == uint64_t())
-        .def(py::self < uint64_t()).def(py::self <= uint64_t())
-        .def(py::self > uint64_t()).def(py::self >= uint64_t())
-
-//        .def_property_readonly("str", &PyCommonCode::string)
-        .def_property_readonly("value", &PyCommonCode::value)
-        .def_property_readonly("short_code", &PyCommonCode::short_code)
-
-        .def("next_cases", &PyCommonCode::next_cases)
-
-        .def("to_string", &PyCommonCode::string, py::arg("shorten") = false)
-
-        .def_static("check", static_cast<bool (*)(uint64_t)>(&PyCommonCode::check))
-        .def_static("check", static_cast<bool (*)(std::string_view)>(&PyCommonCode::check));
-}
diff --git a/src/core_ffi/python_ffi/binder/fast_cal.cc b/src/core_ffi/python_ffi/binder/fast_cal.cc
index b2d0397..e37ac7d 100644
--- a/src/core_ffi/python_ffi/binder/fast_cal.cc
+++ b/src/core_ffi/python_ffi/binder/fast_cal.cc
@@ -2,6 +2,20 @@
 
 #include "binder.h"
 
+#include "py_ffi/cases.h"
+#include "py_ffi/group.h"
+#include "py_ffi/short_code.h"
+#include "py_ffi/common_code.h"
+#include "py_ffi/fast_cal.h"
+
+using klotski::ffi::PyCases;
+using klotski::ffi::PyCasesIter;
+using klotski::ffi::PyShortCode;
+using klotski::ffi::PyCommonCode;
+using klotski::ffi::PyGroupUnion;
+using klotski::ffi::PyGroup;
+using klotski::ffi::PyFastCal;
+
 void bind_fast_cal(const py::module_ &m) {
     py::class_<PyFastCal>(m, "FastCal")
         .def(py::init<PyCommonCode>())
diff --git a/src/core_ffi/python_ffi/binder/group.cc b/src/core_ffi/python_ffi/binder/group.cc
index e2cf410..373a210 100644
--- a/src/core_ffi/python_ffi/binder/group.cc
+++ b/src/core_ffi/python_ffi/binder/group.cc
@@ -1,5 +1,19 @@
 #include "binder.h"
 
+#include "py_ffi/cases.h"
+#include "py_ffi/group.h"
+#include "py_ffi/short_code.h"
+#include "py_ffi/common_code.h"
+#include "py_ffi/fast_cal.h"
+
+using klotski::ffi::PyCases;
+using klotski::ffi::PyCasesIter;
+using klotski::ffi::PyShortCode;
+using klotski::ffi::PyCommonCode;
+using klotski::ffi::PyGroupUnion;
+using klotski::ffi::PyGroup;
+using klotski::ffi::PyFastCal;
+
 void bind_group(const py::module_ &m) {
     py::class_<PyGroup>(m, "Group")
         .def_property_readonly("type_id", &PyGroup::type_id)
diff --git a/src/core_ffi/python_ffi/binder/group_union.cc b/src/core_ffi/python_ffi/binder/group_union.cc
index 5b7329d..54aa5be 100644
--- a/src/core_ffi/python_ffi/binder/group_union.cc
+++ b/src/core_ffi/python_ffi/binder/group_union.cc
@@ -1,5 +1,21 @@
 #include "binder.h"
 
+#include "py_ffi/cases.h"
+#include "py_ffi/group.h"
+#include "py_ffi/short_code.h"
+#include "py_ffi/common_code.h"
+#include "py_ffi/fast_cal.h"
+
+using klotski::ffi::PyCases;
+using klotski::ffi::PyCasesIter;
+using klotski::ffi::PyShortCode;
+using klotski::ffi::PyCommonCode;
+using klotski::ffi::PyGroupUnion;
+using klotski::ffi::PyGroup;
+using klotski::ffi::PyFastCal;
+
+// TODO: move `bind_group` here
+
 void bind_group_union(const py::module_ &m) {
     py::class_<PyGroupUnion>(m, "GroupUnion")
         .def(py::init<uint8_t>())
diff --git a/src/core_ffi/python_ffi/binder/cases.cc b/src/core_ffi/python_ffi/binder/klsk_cases.cc
similarity index 60%
rename from src/core_ffi/python_ffi/binder/cases.cc
rename to src/core_ffi/python_ffi/binder/klsk_cases.cc
index 8300caf..ebc3f07 100644
--- a/src/core_ffi/python_ffi/binder/cases.cc
+++ b/src/core_ffi/python_ffi/binder/klsk_cases.cc
@@ -1,6 +1,12 @@
+#include <pybind11/operators.h>
+
 #include "binder.h"
+#include "py_ffi/cases.h"
+
+using klotski::ffi::PyCases;
+using klotski::ffi::PyCasesIter;
 
-void bind_cases(const py::module_ &mod) {
+static void bind_cases(const py::module_ &mod) {
     py::class_<PyCases>(mod, "Cases")
         .def(py::self == py::self)
         .def("__len__", &PyCases::size)
@@ -10,7 +16,14 @@ void bind_cases(const py::module_ &mod) {
         .def_property_readonly_static("all_cases", [](const py::object&) {
             return PyCases::all_cases();
         });
+}
 
+static void bind_cases_iter(const py::module_ &mod) {
     py::class_<PyCasesIter>(mod, "CasesIter")
         .def("__next__", &PyCasesIter::next);
 }
+
+void bind_klsk_cases(const py::module_ &mod) {
+    bind_cases(mod);
+    bind_cases_iter(mod);
+}
diff --git a/src/core_ffi/python_ffi/binder/klsk_code.cc b/src/core_ffi/python_ffi/binder/klsk_code.cc
new file mode 100644
index 0000000..7d39846
--- /dev/null
+++ b/src/core_ffi/python_ffi/binder/klsk_code.cc
@@ -0,0 +1,72 @@
+#include <pybind11/operators.h>
+
+#include "binder.h"
+#include "py_ffi/short_code.h"
+#include "py_ffi/common_code.h"
+
+using klotski::ffi::PyShortCode;
+using klotski::ffi::PyCommonCode;
+
+static void bind_common_code(const py::module_ &mod) {
+    py::class_<PyCommonCode>(mod, "Code")
+        .def(py::init<uint64_t>())
+        .def(py::init<PyShortCode>())
+        .def(py::init<std::string_view>())
+
+        .def(py::self == py::self)
+        .def(py::self < py::self).def(py::self <= py::self)
+        .def(py::self > py::self).def(py::self >= py::self)
+        .def(py::self == uint64_t())
+        .def(py::self < uint64_t()).def(py::self <= uint64_t())
+        .def(py::self > uint64_t()).def(py::self >= uint64_t())
+
+        .def(py::hash(py::self))
+        .def("__str__", &PyCommonCode::str)
+        .def("__int__", &PyCommonCode::value)
+        .def("__repr__", &PyCommonCode::repr)
+
+        .def("next_cases", &PyCommonCode::next_cases)
+        // TODO: add fast_cal / fast_cal_multi / ...
+
+        .def("to_short_code", &PyCommonCode::short_code)
+        .def("to_string", &PyCommonCode::string, py::arg("shorten") = false)
+
+        .def_property_readonly("value", &PyCommonCode::value)
+        // TODO: add n_1x1 / n_1x2 / n_2x1 / ...
+
+        .def_static("check", py::overload_cast<uint64_t>(&PyCommonCode::check))
+        .def_static("check", py::overload_cast<std::string_view>(&PyCommonCode::check));
+}
+
+static void bind_short_code(const py::module_ &mod) {
+    py::class_<PyShortCode>(mod, "ShortCode")
+        .def(py::init<uint32_t>())
+        .def(py::init<PyCommonCode>())
+        .def(py::init<std::string_view>())
+
+        .def(py::self == py::self)
+        .def(py::self < py::self).def(py::self <= py::self)
+        .def(py::self > py::self).def(py::self >= py::self)
+        .def(py::self == uint32_t())
+        .def(py::self < uint32_t()).def(py::self <= uint32_t())
+        .def(py::self > uint32_t()).def(py::self >= uint32_t())
+
+        .def(py::hash(py::self))
+        .def("__str__", &PyShortCode::str)
+        .def("__int__", &PyShortCode::value)
+        .def("__repr__", &PyShortCode::repr)
+
+        .def_property_readonly("value", &PyShortCode::value)
+
+        .def("to_common_code", &PyShortCode::common_code)
+
+        .def_static("check", py::overload_cast<uint32_t>(&PyShortCode::check))
+        .def_static("check", py::overload_cast<std::string_view>(&PyShortCode::check))
+
+        .def_static("speed_up", &PyShortCode::speed_up, py::arg("fast_mode") = false);
+}
+
+void bind_klsk_code(const py::module_ &mod) {
+    bind_short_code(mod);
+    bind_common_code(mod);
+}
diff --git a/src/core_ffi/python_ffi/binder/short_code.cc b/src/core_ffi/python_ffi/binder/short_code.cc
deleted file mode 100644
index ba47532..0000000
--- a/src/core_ffi/python_ffi/binder/short_code.cc
+++ /dev/null
@@ -1,28 +0,0 @@
-#include "binder.h"
-
-void bind_short_code(const py::module_ &m) {
-    py::class_<PyShortCode>(m, "ShortCode")
-        .def(py::init<uint32_t>())
-        .def(py::init<PyCommonCode>())
-        .def(py::init<std::string_view>())
-
-        .def(py::hash(py::self))
-        .def("__str__", &PyShortCode::str)
-        .def("__int__", &PyShortCode::value)
-        .def("__repr__", &PyShortCode::repr)
-
-        .def(py::self == py::self)
-        .def(py::self < py::self).def(py::self <= py::self)
-        .def(py::self > py::self).def(py::self >= py::self)
-
-        .def(py::self == uint32_t())
-        .def(py::self < uint32_t()).def(py::self <= uint32_t())
-        .def(py::self > uint32_t()).def(py::self >= uint32_t())
-
-        .def_property_readonly("value", &PyShortCode::value)
-        .def_property_readonly("common_code", &PyShortCode::common_code)
-
-        .def_static("check", static_cast<bool (*)(uint32_t)>(&PyShortCode::check))
-        .def_static("check", static_cast<bool (*)(std::string_view)>(&PyShortCode::check))
-        .def_static("speed_up", &PyShortCode::speed_up, py::arg("fast_mode") = false);
-}
diff --git a/src/core_ffi/python_ffi/include/binder.h b/src/core_ffi/python_ffi/include/binder.h
index 5d62e9d..535fe8e 100644
--- a/src/core_ffi/python_ffi/include/binder.h
+++ b/src/core_ffi/python_ffi/include/binder.h
@@ -1,30 +1,15 @@
 #pragma once
 
 #include <pybind11/pybind11.h>
-#include <pybind11/operators.h>
-#include <pybind11/stl.h>
 
 namespace py = pybind11;
 
-#include "py_ffi/cases.h"
-#include "py_ffi/group.h"
-#include "py_ffi/short_code.h"
-#include "py_ffi/common_code.h"
-#include "py_ffi/fast_cal.h"
+void bind_klsk_code(const py::module_ &mod);
 
-using klotski::ffi::PyCases;
-using klotski::ffi::PyCasesIter;
-using klotski::ffi::PyShortCode;
-using klotski::ffi::PyCommonCode;
-using klotski::ffi::PyGroupUnion;
-using klotski::ffi::PyGroup;
-using klotski::ffi::PyFastCal;
+void bind_klsk_cases(const py::module_ &mod);
 
-void bind_cases(const py::module_ &mod);
-void bind_short_code(const py::module_ &m);
-void bind_common_code(const py::module_ &m);
+// TODO: add `bind_klsk_group` and `bind_klsk_fast_cal`
 
 void bind_group_union(const py::module_ &m);
 void bind_group(const py::module_ &m);
-
 void bind_fast_cal(const py::module_ &m);
diff --git a/src/core_ffi/python_ffi/include/py_ffi/cases.h b/src/core_ffi/python_ffi/include/py_ffi/cases.h
index 75fe1b0..ca44870 100644
--- a/src/core_ffi/python_ffi/include/py_ffi/cases.h
+++ b/src/core_ffi/python_ffi/include/py_ffi/cases.h
@@ -3,8 +3,7 @@
 #pragma once
 
 #include <variant>
-
-#include "ranges/ranges.h"
+#include <ranges/ranges.h>
 
 #include "py_ffi/common_code.h"
 
@@ -30,6 +29,8 @@ class PyCases {
 public:
     PyCases() = delete;
 
+    // TODO: add pickle support
+
     // ------------------------------------------------------------------------------------- //
 
     /// Constructing from r-value.
diff --git a/src/core_ffi/python_ffi/include/py_ffi/common_code.h b/src/core_ffi/python_ffi/include/py_ffi/common_code.h
index 52ce799..2a230ea 100644
--- a/src/core_ffi/python_ffi/include/py_ffi/common_code.h
+++ b/src/core_ffi/python_ffi/include/py_ffi/common_code.h
@@ -7,11 +7,9 @@
 
 #include "py_ffi/short_code.h"
 
-namespace klotski::ffi {
-
-using codec::CommonCode;
+// TODO: maybe using `PyLayout` instead of `PyCommonCode`
 
-class PyShortCode;
+namespace klotski::ffi {
 
 class PyCommonCode {
 public:
@@ -57,21 +55,17 @@ public:
 
     // ------------------------------------------------------------------------------------- //
 
-    [[nodiscard]] std::vector<PyCommonCode> next_cases() const noexcept {
-        std::vector<PyCommonCode> cases;
-        auto mover = mover::MaskMover([&cases](const codec::RawCode code, uint64_t) {
-            cases.emplace_back(std::bit_cast<PyCommonCode>(code.to_common_code()));
-        });
-        mover.next_cases(code_.to_raw_code(), 0);
-        return cases;
-    }
+    [[nodiscard]] std::vector<PyCommonCode> next_cases() const noexcept;
 
     // ------------------------------------------------------------------------------------- //
 
 private:
-    CommonCode code_;
+    codec::CommonCode code_;
 };
 
+static_assert(std::is_trivially_copyable_v<PyCommonCode>);
+static_assert(sizeof(PyCommonCode) == sizeof(codec::CommonCode));
+
 // ----------------------------------------------------------------------------------------- //
 
 constexpr auto operator==(const PyCommonCode &lhs, const uint64_t rhs) {
@@ -94,17 +88,9 @@ constexpr auto operator<=>(const PyCommonCode &lhs, const PyCommonCode &rhs) {
 
 } // namespace klotski::ffi
 
-// ----------------------------------------------------------------------------------------- //
-
-namespace std {
-
 template <>
-struct hash<klotski::ffi::PyCommonCode> {
-    size_t operator()(const klotski::ffi::PyCommonCode &common_code) const noexcept {
-        return std::hash<uint64_t>{}(common_code.value());
+struct std::hash<klotski::ffi::PyCommonCode> {
+    size_t operator()(const klotski::ffi::PyCommonCode &code) const noexcept {
+        return std::hash<uint64_t>{}(code.value());
     }
 };
-
-} // namespace std
-
-// ----------------------------------------------------------------------------------------- //
diff --git a/src/core_ffi/python_ffi/include/py_ffi/fast_cal.h b/src/core_ffi/python_ffi/include/py_ffi/fast_cal.h
index 656a8a5..746caf6 100644
--- a/src/core_ffi/python_ffi/include/py_ffi/fast_cal.h
+++ b/src/core_ffi/python_ffi/include/py_ffi/fast_cal.h
@@ -13,7 +13,7 @@ using fast_cal::FastCal;
 class PyFastCal {
 public:
     explicit PyFastCal(PyCommonCode code)
-        : fast_cal_(FastCal(std::bit_cast<CommonCode>(code).to_raw_code())) {}
+        : fast_cal_(FastCal(std::bit_cast<codec::CommonCode>(code).to_raw_code())) {}
 
     // TODO: export solution path directly
     std::optional<PyCommonCode> solve() {
@@ -32,7 +32,7 @@ public:
 
     [[nodiscard]] std::vector<PyCommonCode> backtrack(PyCommonCode code) const {
         std::vector<PyCommonCode> path;
-        for (auto x : fast_cal_.backtrack(std::bit_cast<CommonCode>(code).to_raw_code())) {
+        for (auto x : fast_cal_.backtrack(std::bit_cast<codec::CommonCode>(code).to_raw_code())) {
             path.emplace_back(std::bit_cast<PyCommonCode>(x.to_common_code()));
         }
         return path;
diff --git a/src/core_ffi/python_ffi/include/py_ffi/short_code.h b/src/core_ffi/python_ffi/include/py_ffi/short_code.h
index 385332e..5a330fa 100644
--- a/src/core_ffi/python_ffi/include/py_ffi/short_code.h
+++ b/src/core_ffi/python_ffi/include/py_ffi/short_code.h
@@ -4,12 +4,8 @@
 
 #include <short_code/short_code.h>
 
-#include "py_ffi/common_code.h"
-
 namespace klotski::ffi {
 
-using codec::ShortCode;
-
 class PyCommonCode;
 
 class PyShortCode {
@@ -55,11 +51,11 @@ public:
 
     /// Build conversion index for ShortCode.
     static void speed_up(const bool fast_mode) { // TODO: move to `SpeedUp`
-        ShortCode::speed_up(fast_mode);
+        codec::ShortCode::speed_up(fast_mode);
     }
 
 private:
-    ShortCode code_;
+    codec::ShortCode code_;
 };
 
 // ----------------------------------------------------------------------------------------- //
@@ -84,17 +80,9 @@ constexpr auto operator<=>(const PyShortCode &lhs, const PyShortCode &rhs) {
 
 } // namespace klotski::ffi
 
-// ----------------------------------------------------------------------------------------- //
-
-namespace std {
-
 template <>
-struct hash<klotski::ffi::PyShortCode> {
-    size_t operator()(const klotski::ffi::PyShortCode &short_code) const noexcept {
-        return std::hash<uint32_t>{}(short_code.value());
+struct std::hash<klotski::ffi::PyShortCode> {
+    size_t operator()(const klotski::ffi::PyShortCode &code) const noexcept {
+        return std::hash<uint32_t>{}(code.value());
     }
 };
-
-} // namespace std
-
-// ----------------------------------------------------------------------------------------- //
diff --git a/src/core_ffi/python_ffi/klotski.cc b/src/core_ffi/python_ffi/klotski.cc
index 117fb3f..a07d604 100644
--- a/src/core_ffi/python_ffi/klotski.cc
+++ b/src/core_ffi/python_ffi/klotski.cc
@@ -1,43 +1,26 @@
-#include <pybind11/pybind11.h>
-// #include <pybind11/stl.h>
-
-// #include "py_ffi/common_code.h"
-// #include "py_ffi/short_code.h"
-// #include "py_ffi/cases.h"
-// #include "py_ffi/group.h"
-
-#include "exception.h"
-
 #include "binder.h"
-
-namespace py = pybind11;
+#include "exception.h"
 
 using klotski::ffi::PyExc_CodecError;
 using klotski::ffi::PyExc_GroupError;
 
 #include "group/group.h"
-#include "all_cases/all_cases.h"
 
 // static PyCases group_demo() {
 //     auto group_union = klotski::group::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<PyExc_GroupError>(m, "GroupError", PyExc_ValueError);
     py::register_exception<PyExc_CodecError>(m, "CodecError", PyExc_ValueError);
 
-    // m.def("all_cases", &all_cases);
     // m.def("group_demo", &group_demo);
 
-    bind_cases(m);
-    bind_short_code(m);
-    bind_common_code(m);
+    bind_klsk_cases(m);
+    bind_klsk_code(m);
+
     bind_group(m);
     bind_group_union(m);
     bind_fast_cal(m);
diff --git a/src/core_ffi/python_ffi/wrapper/common_codec.cc b/src/core_ffi/python_ffi/wrapper/common_codec.cc
index 21489ba..a24ecab 100644
--- a/src/core_ffi/python_ffi/wrapper/common_codec.cc
+++ b/src/core_ffi/python_ffi/wrapper/common_codec.cc
@@ -4,6 +4,8 @@
 #include "py_ffi/common_code.h"
 
 using namespace klotski::ffi;
+using klotski::codec::ShortCode;
+using klotski::codec::CommonCode;
 
 // ----------------------------------------------------------------------------------------- //
 
@@ -31,12 +33,23 @@ bool PyCommonCode::check(const std::string_view code) noexcept {
 
 // ----------------------------------------------------------------------------------------- //
 
+[[nodiscard]] std::vector<PyCommonCode> PyCommonCode::next_cases() const noexcept {
+    std::vector<PyCommonCode> cases;
+    auto mover = mover::MaskMover([&cases](const codec::RawCode code, uint64_t) {
+        cases.emplace_back(std::bit_cast<PyCommonCode>(code.to_common_code()));
+    });
+    mover.next_cases(code_.to_raw_code(), 0);
+    return cases;
+}
+
+// ----------------------------------------------------------------------------------------- //
+
 std::string PyCommonCode::str(const PyCommonCode code) noexcept {
     return code.code_.to_string();
 }
 
 std::string PyCommonCode::repr(const PyCommonCode code) noexcept {
-    return std::format("<klotski.CommonCode 0x{}>", str(code));
+    return std::format("<klotski.Code 0x{}>", str(code));
 }
 
 // ----------------------------------------------------------------------------------------- //
@@ -49,14 +62,14 @@ static CommonCode convert(const uint64_t code) {
     if (CommonCode::check(code)) {
         return CommonCode::unsafe_create(code);
     }
-    throw PyExc_CodecError(std::format("invalid common code -> {}", code));
+    throw PyExc_CodecError(std::format("invalid code: {}", code));
 }
 
 static CommonCode convert(const std::string_view code) {
     if (const auto str = CommonCode::from_string(code)) {
         return str.value();
     }
-    throw PyExc_CodecError(std::format("invalid common code -> `{}`", code));
+    throw PyExc_CodecError(std::format("invalid code: `{}`", code));
 }
 
 PyCommonCode::PyCommonCode(const uint64_t code) : code_(convert(code)) {}
diff --git a/src/core_ffi/python_ffi/wrapper/group_union.cc b/src/core_ffi/python_ffi/wrapper/group_union.cc
index a13ab22..4838516 100644
--- a/src/core_ffi/python_ffi/wrapper/group_union.cc
+++ b/src/core_ffi/python_ffi/wrapper/group_union.cc
@@ -1,6 +1,9 @@
 #include "exception.h"
 #include "py_ffi/group.h"
 
+using klotski::codec::ShortCode;
+using klotski::codec::CommonCode;
+
 using klotski::ffi::PyExc_GroupError;
 
 using klotski::ffi::PyGroupUnion;
diff --git a/src/core_ffi/python_ffi/wrapper/short_code.cc b/src/core_ffi/python_ffi/wrapper/short_code.cc
index 2e85141..bfba390 100644
--- a/src/core_ffi/python_ffi/wrapper/short_code.cc
+++ b/src/core_ffi/python_ffi/wrapper/short_code.cc
@@ -2,8 +2,11 @@
 
 #include "exception.h"
 #include "py_ffi/short_code.h"
+#include "py_ffi/common_code.h"
 
 using namespace klotski::ffi;
+using klotski::codec::ShortCode;
+using klotski::codec::CommonCode;
 
 // ----------------------------------------------------------------------------------------- //