<?php
    if (isset($_POST["username"]) && isset($_POST["password"]))
    {
        $username = $_POST['username'];
        $password = $_POST['password'];

        if($username == 'admin' && $password == 'password'){
            echo "good login";
        }

        else
        {
            echo "bad login";
        }
    }
?>

print(post(url, data={"username": "admin", "password": "blahBlah"}).content)