code: function invoke(collection, methodName) {
      var args = slice(arguments, 2),
          index = -1,
          isFunc = typeof methodName == 'function',
          length = collection ? collection.length : 0,
          result = Array(typeof length == 'number' ? length : 0);
  
      forEach(collection, function(value) {
        result[++index] = (isFunc ? methodName : value[methodName]).apply(value, args);
      });
      return result;
    }
docs: Invokes the method named by `methodName` on each element in the `collection`
  returning an array of the results of each invoked method. Additional arguments
  will be provided to each invoked method. If `methodName` is a function it
  will be invoked for, and `this` bound to, each element in the `collection`.
  
  @static
  @memberOf _
  @category Collections
  @param {Array|Object|string} collection The collection to iterate over.
  @param {Function|string} methodName The name of the method to invoke or
  the function invoked per iteration.
  @param {...*} [arg] Arguments to invoke the method with.
  @returns {Array} Returns a new array of the results of each invoked method.
  @example
  
  _.invoke([[5, 1, 7], [3, 2, 1]], 'sort');
  // => [[1, 5, 7], [1, 2, 3]]
  
  _.invoke([123, 456], String.prototype.split, '');
  // => [['1', '2', '3'], ['4', '5', '6']]