code: function size(collection) {
      if (collection == null) {
        return 0;
      }
      collection = isArrayLike(collection) ? collection : keys(collection);
      return collection.length;
    }
docs: Gets the size of `collection` by returning its length for array-like
  values or the number of own enumerable string keyed properties for objects.
  
  @static
  @memberOf _
  @since 0.1.0
  @category Collection
  @param {Array|Object} collection The collection to inspect.
  @returns {number} Returns the collection size.
  @example
  
  _.size([1, 2, 3]);
  // => 3
  
  _.size({ 'a': 1, 'b': 2 });
  // => 2
  
  _.size('pebbles');
  // => 7