code: function (tx, callback) {
    var prev = 0,
      re = /\s/gi,
      chunk;
    while (re.exec(tx)) {
      chunk = tx.slice(prev, re.lastIndex - 1);
      callback(chunk);
      prev = re.lastIndex - 1;
    }
    if (prev < tx.length) {
      callback(tx.slice(prev));
    }
  }
docs: /*global module