Trying to write values to serial port in python and read them from arduino simultaneoulsy

I want to send some constantly changing values from my Python code in Visual studio to my arduino IDE (mac user by the way). I want the arduino code to read the values as they are being sent, instead of having to run the code in python, close the window, and then open up the arduino IDE after.

Essentially, I want Visual Studio to write to the serial port whilst Arduino is reading from it.

At the moment, the python side is working fully- I'm using pyserial and when I ask my python code to read me the values it has written to the serial port, it works. However, when I try to open up the arduino IDE and run the code, it says 'port busy'. I can't run the python code if the arduino IDE is open either, it returns the same sort of error message.

Does anyone know how I can solve this? Thanks

Python code:

import serial #arduinostuff
import time
arduino = serial.Serial(port='/dev/cu.usbmodem14101', baudrate=115200, timeout=.1)

# Project: Object Tracking
# Author: Addison Sears-Collins 
# Website: https://automaticaddison.com
# Date created: 06/13/2020
# Python version: 3.7
def write_read(x):
    arduino.write(bytes(str(x), 'utf-8'))
    time.sleep(0.05)
    data = arduino.readline()
    return data

Arduino code:

int x;

void setup() {
  Serial.begin(115200);
  Serial.setTimeout(1);
}

void loop() {
    if(Serial.available() > 0) {
        char data = Serial.read();
        char str[2];
        str[0] = data;
        str[1] = '\0';
        Serial.print(str);
    }
}

source https://stackoverflow.com/questions/74605964/trying-to-write-values-to-serial-port-in-python-and-read-them-from-arduino-simul