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constexpr cancellation_type_t operator()() const; » more... template< typename E, typename... Args> constexpr constraint_t< !is_same< decay_t< E >, asio::error_code >::value &&!is_same< decay_t< E >, std::exception_ptr >::value, cancellation_type_t > operator()( const E & , Args && ...) const; » more... template< typename E, typename... Args> constexpr constraint_t< is_same< decay_t< E >, asio::error_code >::value||is_same< decay_t< E >, std::exception_ptr >::value, cancellation_type_t > operator()( const E & e, Args && ...) const; » more...