auto echo(tcp_connection connection) noexcept -> task<void> {
    char            buffer[4096];
    size_t          bytes;
    std::error_code error;

    for (;;) {
        error = co_await connection.receive(buffer, sizeof(buffer), bytes);
        // Handle errors.
        if (bytes == 0) 
            // Connection closed.

        error = co_await connection.send(buffer, bytes, bytes);
        // Handle errors.
    }
    co_return;
}

auto acceptor(io_context &io_ctx, tcp_server server) noexcept -> task<void> {
    std::error_code error;
    tcp_connection  connection;
    for (;;) {
        error = co_await server.accept(connection);
        // Handle errors.
        io_ctx.execute(echo(std::move(connection)));
    }
}