Cannot access C++ extension module and its methods from python created using SWIG

Created an empty c++ in visual studio 2017 added the following files with following C++ methods

//gfg.c

#include <stdio.h> 
#include <math.h> 

//our header file 
#include "gfg.h" 
#define ll long long 

double myvar = 3.4;

// calculate factorial 
ll int fact(ll int n)
{
    if (n <= 1)
        return 1;
    else
        return (n * fact(n - 1));
}

//find mod 
int my_mod(int n, int m)
{
    return(n % m);
}

//gfg.h

#pragma once

long long int fact(long long int n);
int my_mod(int n, int m);

//gfg.i for swig

/* file : gfg.i */

/* name of module to use*/
%module gfg 
%{ 
    /* Every thing in this file is being copied in  
     wrapper file. We include the C header file necessary 
     to compile the interface */
    #include "gfg.h" 

    /* variable declaration*/
    double myvar; 
%} 

/* explicitly list functions and variables to be interfaced */
double myvar; 
long long int fact(long long int n1); 
int my_mod(int m, int n); 

/* or if we want to interface all functions then we can simply 
   include header file like this -  
   %include "gfg.h" 
*/

Added custom action for gfg.i file as below with output file name as gfg_wrap.c

$(SWIG_PATH)\swig.exe -python gfg.i

while compiling gfg.i file, it given two outputs gfg.py and gfg_wrap.c.

then i created Setup.py file with the following contents

# File : setup.py 

from distutils.core import setup, Extension 
#name of module 
name  = "gfg"

#version of module 
version = "1.0"

# specify the name of the extension and source files 
# required to compile this 
ext_modules = Extension(name='_gfg',sources=["gfg.i","gfg.c"]) 

setup(name=name, 
      version=version, 
      ext_modules=[ext_modules]) 

#C:\Python37\python_d.exe setup.py build_ext --inplace

with custom action as

C:\Python37\python_d.exe setup.py build_ext --inplace

this python directory contains swig.exe

after executing this, it generated an _gfg_d.cp37-win_amd64.pyd file in the project directory.

when given import gfg from CMD it shown the following error.

I was trying to access fact method from gfg.h Is there something iam missing out?