code: function size(collection) {
          if (collection == null) {
            return 0;
          }
          if (isArrayLike(collection)) {
            var result = collection.length;
            return result && isString(collection) ? stringSize(collection) : result;
          }
          return keys(collection).length;
        }
docs: Gets the size of `collection` by returning its length for array-like
  values or the number of own enumerable properties for objects.
  
  @static
  @memberOf _
  @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