example.py

from flask import Flask, request
app = Flask(__name__)

@app.route("/", methods=["POST"])
def base():
    if request.form.get("arg1"):
        return option1()
    elif request.form.get("arg2"):
        return option2()
    else:
        return option3()

def option1():
    return "option1"

def option2():
    return "option2"

def option3():
    return "option3"