Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

boost/concept/detail/backward_compatibility.hpp

// Copyright David Abrahams 2009. 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)
#ifndef BOOST_CONCEPT_BACKWARD_COMPATIBILITY_DWA200968_HPP
# define BOOST_CONCEPT_BACKWARD_COMPATIBILITY_DWA200968_HPP

namespace boost
{
  namespace concepts {}

# if defined(BOOST_HAS_CONCEPTS) && !defined(BOOST_CONCEPT_NO_BACKWARD_KEYWORD)
  namespace concept = concepts;
# endif 
} // namespace boost::concept

#endif // BOOST_CONCEPT_BACKWARD_COMPATIBILITY_DWA200968_HPP