std::future::future
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | future(); | (1) | (since C++11) | 
| future( future&& other ); | (2) | (since C++11) | 
| future( const future& other ) = delete; | (3) | (since C++11) | 
Constructs a std::future object.
1) Default constructor. Constructs a 
std::future with no shared state.  After construction, valid() == false.
2) Move constructor. Constructs a 
std::future with the shared state of other using move semantics. After construction, other.valid() == false.[edit] Parameters
| other | - | another std::futureto acquire shared state from | 
[edit] Exceptions
1-2) 
noexcept specification:  
noexcept