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        A type trait that determines whether a require expression is
        well-formed.
      
template<
    typename T,
    typename... Properties>
struct can_require
        Class template can_require is a trait that is derived from
        true_type if the expression asio::require(std::declval<T>(),
        std::declval<Properties>()...) is well formed; otherwise false_type.
      
        Header: asio/require.hpp
      
        Convenience header: asio.hpp