code: function size(collection) {
        if (collection == null) {
          return 0;
        }
        if (isArrayLike(collection)) {
          return isString(collection) ? stringSize(collection) : collection.length;
        }
        var tag = getTag(collection);
        if (tag == mapTag || tag == setTag) {
          return collection.size;
        }
        return baseKeys(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|string} 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