code: function functions(arr, i) {
    var values = filterType(arr, 'function');
    return i ? values[i] : values;
  }
docs: Filter `array`, returning only the functions.
  
  ```js
  var one = function() {};
  var two = function() {};
  var arr = ['a', {a: 'b'}, 1, one, 'b', 2, {c: 'd'}, two, 'c'];
  
  utils.functions(arr);
  //=> [one, two]
  ```
  
  @param  {Array} `array`
  @param  {Array} `index` Optionally specify the index of the function to return, otherwise all functions are returned.
  @return {Array} Array of functions or empty array.
  @api public