where are they? what do they look like?

add_icons.js

const possibleIcons = [
  'twitter-bird',
  'mention',
  'following',
  'message',
  'home',
  'hashtag',
  'reply',
  'favorite',
  'retweet',
  'retweet-filled',
  'drafts',
  'search',
  'trash',
  'close',
  'arrow-r',
  'caretRight',
  'arrow-l',
  'caretLeft',
  'protected',
  'list',
  'list-filled',
  'camera',
  'more',
  'settings',
  'notifications',
  'user-dd',
  'activity',
  'trending',
  'minus',
  'plus',
  'geo',
  'check',
  'schedule',
  'dot',
  'user',
  'user-filled',
  'content',
  'arrow-d',
  'caretDown',
  'arrow-u',
  'share',
  'info',
  'verified',
  'translator',
  'blocked',
  'constrain',
  'play-video',
  'empty',
  'clear-input',
  'compose',
  'mark-read',
  'arrow-r-double',
  'arrow-l-double',
  'follow',
  'image',
  'popout',
  'move',
  'compose-grid',
  'compose-minigrid',
  'compose-list',
  'edit',
  'clear-timeline',
  'sliders',
  'custom-timeline',
  'compose-dm',
  'bg-dot',
  'user-team-mgr',
  'user-switch',
  'conversation',
  'dataminr',
  'link',
  'flash',
  'pointer-u',
  'analytics',
  'heart',
  'calendar',
  'attachment',
  'play',
  'bookmark',
  'play-badge',
  'gif-badge',
  'poll',
  'lightning',
  'heart-filled',
  'toggle-off',
  'toggle-on',
];
let allItems = '';
possibleIcons.forEach((element) => {
  allItems += `
    <li class="tweet-action-item btd-tweet-action-item pull-left margin-r--13 margin-l--1">
      <a class="js-show-tip tweet-action btd-tweet-action btd-clipboard position-rel" href="#" 
        data-btd-action="meme-${element}" rel="${element}" title=" ${element} "> 
        <i class="js-icon-${element} icon icon-${element} icon-${element}-toggle txt-center"></i>
        <span class="is-vishidden"> {{_i}}${element}{{/i}} </span>
      </a>
    </li>`;
});

tweetdeck_icons.md

embedded in a tweet

in FontForge