std::experimental::ranges::IndirectlyComparable
来自cppreference.com
                    
                                        
                    < cpp | experimental | ranges
                    
                                                            
                    |   template < class I1, class I2, class R = ranges::equal_to<>,            class P1 = ranges::identity, class P2 = ranges::identity >  | 
(范围 TS) | |
| 本节未完成 原因:添加描述和额外通告  |