no access allow control origin header react flask code example

Example: ccess to XMLHttpRequest at 'http://127.0.0.1:5000/ has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

@app.route('your route', methods=['GET'])
def yourMethod(params):
    response = flask.jsonify({'some': 'data'})
    response.headers.add('Access-Control-Allow-Origin', '*')
    return response