PHP - GUMP验证类

I need to use the GUMP validation class to validate my form data but how to get each field error seperately

How to show up each field error

<?php

    if (isset($_POST['submit'])){
        require "gump.class.php";
        $validator = new GUMP();
        $us = $_POST['username'];
        $pwd = $_POST['password'];
        // Set the data
        $_POST = array('username' => $us,'password' => $pwd);
        $_POST = $validator->sanitize($_POST);
        $rules = array('username' => 'required','password' => 'required|max_len,100|min_len,6');
        $filters = array('username' => 'trim|sanitize_string','password' => 'trim|base64_encode');
        $_POST = $validator->filter($_POST, $filters);
        $validated = $validator->validate($_POST, $rules);

        if ($validated === TRUE){
            echo "Successful Validation

";
            print_r($_POST);
            exit;
        } else {
            echo $validator->get_readable_errors(true);
        }

    }

    ?>

Reffering to github code, there is get_errors_array method, that should return an array of errors with field names as keys