diff --git a/motivating_sequence.md b/motivating_sequence.md
new file mode 100644
index 0000000..1d88f04
--- /dev/null
+++ b/motivating_sequence.md
@@ -0,0 +1,68 @@
+# Advantage of using PySequence internally.
+
+CPython provides an API to handle any type of
+sequence by the same interface:
+
+* PySequence_Check
+* PySequence_GetItem
+
+or similar methods.
+
+Currenty the main effect on user side is that one does not need to call
+`list(obj)` when returning an object. Its main use is for array as
+a large array does not be converted to a list before passing it
+as output.
+
+
+```
+# record for reference waveform
+record(pycalc, "ref_wf")
+{
+   field(DESC, "reference waveform")
+   field(CALC, "( A * np.sin(B * (C + np.asarray(D)) ) ).tolist()")
+   #field(CALC, "test_pydev.calc(%A%, %B%, %C%, %D%, tpro=%TPRO%) ")
+   field(INPA, "src:amp")
+   field(INPB, "src:frq")
+   field(INPC, "src:phs")
+   field(INPD, "src:t")
+   field(FTA, "DOUBLE")
+   field(FTB, "DOUBLE")
+   field(FTC, "DOUBLE")
+   field(FTD, "DOUBLE")
+   field(MED, 64)
+   field(MEVL, 64)
+   field(FTVL, "DOUBLE")
+   field(TPRO, 1)
+}
+
+record(waveform, "src:t")
+{
+    field(DTYP, "pydev")
+    field(INP, "@np.linspace(0, 2*np.pi, num=64 + 1).tolist()")
+    field(FTVL, "DOUBLE")
+    field(NELM, 64)
+    field(PINI, "YES")
+    field(FLNK, "ref_wf")
+}
+
+record(ao, "src:amp")
+{
+    field(VAL, 1.0)
+    field(FLNK, "ref_wf")
+}
+
+record(ao, "src:frq")
+{
+    field(VAL, 2.0)
+    field(FLNK, "ref_wf")
+}
+
+record(ao, "src:phs")
+{
+    field(VAL, 0)
+    field(FLNK, "ref_wf")
+}
+
+
+
+```
diff --git a/src/pywrapper.cpp b/src/pywrapper.cpp
index d96a91a..625b4ee 100644
--- a/src/pywrapper.cpp
+++ b/src/pywrapper.cpp
@@ -6,6 +6,11 @@
 #include "pywrapper.h"
 #include "util.h"
 
+#if PY_MAJOR_VERSION >= 3
+#if PY_MINOR_VERSION >= 2
+#define Py_LIMITED_API
+#endif // PY_MINOR_VERSION >= 2
+#endif // PY_MAJOR_VERSION >= 3
 #include <Python.h>
 
 #include <map>
@@ -270,14 +275,14 @@ bool PyWrapper::convert(void* in_, Variant& out)
         return true;
     }
 
-    if (PyList_Check(in)) {
+    if (PySequence_Check(in)) {
         std::vector<double> vd;
         std::vector<long long int> vl;
         std::vector<std::string> vs;
         Variant::Type t = Variant::Type::NONE;
 
-        for (Py_ssize_t i = 0; i < PyList_Size(in); i++) {
-            PyObject* el = PyList_GetItem(in, i);
+        for (Py_ssize_t i = 0; i < PySequence_Size(in); i++) {
+            PyObject* el = PySequence_GetItem(in, i);
 #if PY_MAJOR_VERSION < 3
             if (PyInt_Check(el) && (t == Variant::Type::NONE || t == Variant::Type::VECTOR_LONG)) {
                 long long val = PyInt_AsLong(el);
diff --git a/src/unittest/test_pywrapper.cpp b/src/unittest/test_pywrapper.cpp
index 82129ce..55ecbe6 100644
--- a/src/unittest/test_pywrapper.cpp
+++ b/src/unittest/test_pywrapper.cpp
@@ -82,6 +82,11 @@ struct TestPyWrapper {
         testOk1(PyWrapper::exec("[1,2,3]").get_unsigned_array() == cmpulli);
         testOk1(PyWrapper::exec("[1,2,3]").get_double_array() == cmpd);
         testOk1(PyWrapper::exec("[1,2,3]").get_string_array() == cmps);
+
+	// tuple as input ...
+	testOk1(PyWrapper::exec("(1,2,3)").get_long_array() == cmplli);
+
+
     }
 };