const GMAILS_EMAILS = ``.toLowerCase();  // List of emails from GMail to: line.

const GMAIL_EMAILS = GMAILS_EMAILS.split(',\n').map(
  email => email.substring(
    email.indexOf("<") + 1, 
    email.lastIndexOf(">")
  ));

const GROUPS_EMAILS = ``.toLowerCase();  // List of emails from Groups CSV download.

const GROUP_EMAILS = GROUPS_EMAILS.split('\n').map(
  row => row.split(',')[0]);

const GROUP_NOT_GMAIL = GROUP_EMAILS.filter(
  x => !GMAIL_EMAILS.includes(x));
console.log(`Missing ${GROUP_NOT_GMAIL} from GMail emails.`);

const GMAIL_NOT_GROUP = GMAIL_EMAILS.filter(
  x => !GROUP_EMAILS.includes(x));
console.log(`Missing ${GMAIL_NOT_GROUP} from Group emails.`);