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[/
Boost.Optional
Copyright (c) 2003-2007 Fernando Luis Cacciola Carballal
Copyright (c) 2015 Andrzej Krzemienski
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
]
[section Header <boost/none.hpp>]
[section Synopsis]
```
namespace boost {
class none_t {/* see below */};
const none_t none (/* see below */);
} // namespace boost
```
Class `none_t` is meant to serve as a tag for selecting appropriate overloads of from `optional`'s interface. It is an empty, trivially copyable class with disabled default constructor.
Constant `none` is used to indicate an optional object that does not contain a value in initialization, assignment and relational operations of `optional`.
[endsect]
[endsect]
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