docs: function uniq(arr) {
    if (arr == null || arr.length === 0) {
      return [];
    }
  
    return _.reduce(arr, function(acc, ele) {
      var letter = exclusions.singleLetters;
  
      if (acc.indexOf(ele) === -1 && letter.indexOf(ele) === -1) {
        acc.push(ele);
      }
      return acc;
    }, []);
  }