std::optional::operator bool, std::optional::has_value
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                    | constexpr explicit operator bool() const; | (since C++17) | |
| constexpr bool has_value() const; | (since C++17) | |
Checks whether *this contains a value.
[edit] Parameters
(none)
[edit] Return value
true if *this contains a value, false if *this does not contain a value.
[edit] Exceptions
noexcept specification:  
noexcept
  

