Pyshell.end is not executing. I am working on this code but pyshell.end doesn't get executed, although I've used next(). It looks like system is stuck on pyshell.on and doesn't move on pyshell.end.

app.post('/app/blogTitle', (req, res, next)=>{
const keywords = req.body.keywords;
const description = req.body.description;
var pyshell = new PythonShell('./Python Files/Titles/run.py');
pyshell.send(JSON.stringify(description));

pyshell.on('message', async function (message) {
  // received a message sent from the Python script 
  arr= await message;
  if (arr.length!==0){
    console.log("Result successfully obtained");
    res.status(200).json(arr);
  }
  else{
    console.log("Some error occurred");
    res.status(500).json({
    msg: 'Server error'
    })
  }
  next();
});

// end the input stream and allow the process to exit
pyshell.end( function (err) {
  if (err){
      throw err;
  };
  console.log('finished');
})
})