std::experimental::latch::latch
From cppreference.com
                    
                                        
                    < cpp | experimental | latch
                    
                                                            
                    | explicit latch( ptrdiff_t value ); | (1) | (concurrency TS) | 
| latch( const latch & ) = delete; | (2) | (concurrency TS) | 
1) Constructs a 
latch and initializes its internal counter.2) Copy constructor is deleted. 
latch is not copyable.[edit] Parameters
| value | - | the initial value of the internal counter; must be non-negative | 


