std::experimental::optional::value
From cppreference.com
                    
                                        
                    < cpp | experimental | optional
                    
                                                            
                    | constexpr const T& value() const; | (library fundamentals TS) | |
| T& value(); | (library fundamentals TS) | |
Returns the contained value.
| Contents | 
[edit] Parameters
(none)
[edit] Return value
A reference to the contained value.
[edit] Exceptions
std::bad_optional_access if *this is in disengaged state.
[edit] See also
| returns the contained value if engaged, another value otherwise (public member function) | 


