[USER SUBMITTED GUIDE] How to access the new MAL API using OAuth 2.0

import requests

parameters = {
    'client_id': '...CLIENT ID...',
    'client_secret': '...CLIENT SECRET...',
    'code': '...CODE...',
    'code_verifier': '...CODE VERIFIER...',
    'grant_type': 'authorization_code'
    }

response = requests.post('https://myanimelist.net/v1/oauth2/token', data = parameters)

print(response.status_code)  # 200
print(response.text)  # { ...Access Token... }

{
"error":"invalid_grant",
"message":"The provided authorization grant (e.g., authorization code, resource owner credentials) or refresh token is invalid, expired, revoked, does not match the redirection URI used in the authorization request, or was issued to another client.",
"hint":"Failed to verify `code_verifier`."
}

function onComplete() //Don't change anything on this line!
{
    console.log(this.responseText); //Don't change anything on this line!
} //Don't change anything on this line!

const encodeParameters = p => Object.entries(p).map(kv => kv.map(encodeURIComponent).join("=")).join("&"); //Don't change anything on this line!

const request = new XMLHttpRequest(); //Don't change anything on this line!
request.addEventListener("load", onComplete); //Don't change anything on this line!
request.open("POST", "https://cors-anywhere.herokuapp.com/myanimelist.net:443/v1/oauth2/token"); //Don't change anything on this line!
request.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); //Don't change anything on this line!
request.send(encodeParameters({
    client_id: "4f15e1304a37eb59aa1c05eea7c81f4e",
    code: "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", //This needs to be replaced.You will get this on step 2
    code_verifier: "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", //Paste the Generated Code Verifier numbers in the place of "CODE VERIFIER"
    grant_type: "authorization_code" //Don't change anything on this line!
})); //Don't change anything on this line!

function onComplete() //Don't change anything on this line!
{
    console.log(this.responseText); //Don't change anything on this line!
} //Don't change anything on this line!

const encodeParameters = p => Object.entries(p).map(kv => kv.map(encodeURIComponent).join("=")).join("&"); //Don't change anything on this line!

const request = new XMLHttpRequest(); //Don't change anything on this line!
request.addEventListener("load", onComplete); //Don't change anything on this line!
request.open("POST", "https://cors-anywhere.herokuapp.com/myanimelist.net:443/v1/oauth2/token"); //Don't change anything on this line!
request.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); //Don't change anything on this line!
request.send(encodeParameters({
    client_id: "4f15e1304a37eb59aa1c05eea7c81f4e",
    code: "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", //This needs to be replaced.You will get this on step 2
    code_verifier: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA", //Paste the Generated Code Verifier numbers in the place of "CODE VERIFIER"
    grant_type: "authorization_code" //Don't change anything on this line!
})); //Don't change anything on this line!

$postData = http_build_query(array(
    'client_id' => 'YOUR CLIENT ID',
    'client_secret' => 'YOUR CLIENT SECRET',
    'code' => 'AUTHORISATION CODE',
    'code_verifier' => 'CODE VERIFIER',
    'grant_type' => 'authorization_code'
));

$context = stream_context_create(array(
    'http' => array(
        'method' => 'POST',
        'content' => $postData,
        'header'=>  'Content-type: application/x-www-form-urlencoded'
)));

$response = file_get_contents('https://myanimelist.net/v1/oauth2/token', false, $context);

// var_dump(json_decode( $response ));