Solution
from flask import Flask, render_template, request, session
app = Flask(__name__)
app.secret_key = 'change_this! and dont include it in questions!'
first_name = "nothing yet" # this is the initial value when the app runs
@app.route('/', methods =["GET", "POST"])
def gfg():
if request.method == "POST":
global first_name # this will use the global scope for this variable
first_name = request.form.get("fname") # this will update the global variable now!
return "Your new name is " + first_name
return "Your current name is " + first_name
if __name__ == '__main__':
app.run(debug=True)