Python C API: Problems trying to build a dictionary

I'm trying to build a Python dictionary using the C API but it seems it's not possible (Py_BuildValue returns a NULL object) to use a PyObject* as value. I have a situation like the following:

#include <python3.5/Python.h>
...
PyObject *myList = PyList_New(1);
PyList_SetItem(myList, 0, Py_BuildValue("i", 1));
dict = Py_BuildValue("{siso}",
           "anInt", myInt,
           "aList", mylist);

I'm looking for a solution working with generic size of the list. I didn't find anything about this in the official documentation and also googling for hours. Can somebody help me? Thanks in advance

You're using the wrong format spec. Here is an example.

So, in order to build a dictionary, you do it like so:

int a_c_int; // 1
PyObject *a_python_list; // [1]
// ...
Py_BuildValue("{s:i,s:O}",  # note the capital O ;)
          "abc", a_c_int, 
          "def", a_python_list);    

returns the python dict

{'abc': 1, 'def': [1]}