std::experimental::ranges::Invocable, std::experimental::ranges::RegularInvocable
From cppreference.com
                    
                                        
                    < cpp | experimental | ranges
                    
                                                            
                    | Defined in header  <experimental/ranges/concepts> | ||
| template <class F, class... Args> concept bool Invocable() { | (ranges TS) | |
| template <class F, class... Args> concept bool RegularInvocable() { | (ranges TS) | |
| This section is incomplete Reason: add description and extra caveats |