Issue importing other modules

Apps
#1

Hello everyone,
I am new to nodejs and I want to develop a Dapp based on the Animal Kingdom (zero-to-dapp).

Every time I want to use functions from ‘child_process’ with code like ( for example, adding to Landing.js ):

   var exec = require('child_process').exec;
   exec('python3 test.py '+ 123, function (error, stdout, stderr) {
        if(error){
            console.error('error: ' + error);
            return;
        }
        console.log('receive: ' + stdout);
    });

it always fails and shows infomation like:

TypeError: exec is not a function

It seems that it is not imported right. Did I miss some steps or use the wrong way? Any help would be appreciated.