lib/utils/autocomplete.js/getSuggestions
const getSuggestions = (commands, env) => {
  if (!env.complete) return;
  const tokens = env.line.split(/\s+/);
  const { log } = require('tabtab');
  switch (tokens.length) {
    case 1:
    case 2:
      log(Object.keys(commands));
      return;
    case 3:
      if (commands[env.prev]) log(commands[env.prev]);
      return;
    default:
      return;
  }
};