I need help splitting the python c-api module into several files to better structure the project.

The main file module_core.c contains the program code:

#include "my_module.h"


static PyMethodDef init_methods[] = {
    {"hello", init_hello, METH_VARARGS, "Welcome stamp"},
    {NULL, NULL, 0, NULL}
};

static struct PyModuleDef init_module = {
    PyModuleDef_HEAD_INIT,
    "init",
    "Module for displaying a greeting",
    -1,
    init_methods
};

static PyObject* init_init_module(PyObject *module) {

    PyObject* module_dict = PyModule_GetDict(module);
    if (module_dict == NULL) {
        return NULL;
    }

    if (PyEval_EvalCode(Py_CompileString("init.hello()", "<string>", Py_file_input),
                         module_dict, module_dict) == NULL) {
        PyErr_Print();
        return NULL;
    }
    
    PyRun_SimpleString("print(dir())");
    Py_RETURN_NONE;
}

PyMODINIT_FUNC PyInit_init(void) {
    PyObject *m = PyModule_Create(&init_module);
    if (m == NULL)
        return NULL;

    if (PyModule_AddObject(m, "init", m) < 0) { 
        Py_DECREF(m);
        return NULL;
    }

    // Call the function to print "Hello world!" when importing
    if (init_init_module(m) < 0) {
        Py_DECREF(m);
        return NULL;
    }

    return m;
}

the file my_module.h has the following code:

#ifndef MY_MODULE_H
#define MY_MODULE_H

#include <Python.h>

static PyObject* init_hello(PyObject* self, PyObject* args);

#endif

utils.c file has the following code:

#include "my_module.h"


static PyObject* init_hello(PyObject* self, PyObject* args) {
    const char * python_code = "ndef bar():n    print('test from foo')nnnbar()n";
    PyRun_SimpleString("print('Hello, World!')");
    PyRun_SimpleString(python_code);
    Py_RETURN_NONE;
}

build file setup.py

from setuptools import setup, Extension

extensions = [
    Extension(
        "init",
        sources=[
            "my_module/module_core.c",
            "my_module/utils.c",
        ],
        extra_compile_args=["-O2", "-Wall"],
        extra_link_args=[],
        include_dirs=["my_module"],
    ),
]

setup(
    name="init",
    version="1.0.0",
    description="Example Python module using C-API",
    ext_modules=extensions
)

The module compiles successfully, but with warnings. After compiling and importing, the Python interpreter reports an error:

>> import init
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /home/u/work3/app/init.cpython-310-x86_64-linux-gnu.so: undefined symbol: init_hello

Please help me resolve the error.