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Start an asynchronous send.
template< typename ConstBufferSequence, typename WriteToken = default_completion_token_t<executor_type>> DEDUCED async_send_to( const ConstBufferSequence & buffers, const endpoint_type & destination, socket_base::message_flags flags, WriteToken && token = default_completion_token_t< executor_type >());
This function is used to asynchronously send a datagram to the specified remote endpoint. It is an initiating function for an asynchronous operation, and always returns immediately.
One or more data buffers to be sent to the remote endpoint. Although the buffers object may be copied as necessary, ownership of the underlying memory blocks is retained by the caller, which must guarantee that they remain valid until the completion handler is called.
Flags specifying how the send call is to be made.
The remote endpoint to which the data will be sent. Copies will be made of the endpoint as required.
                  The completion
                  token that will be used to produce a completion handler,
                  which will be called when the send completes. Potential completion
                  tokens include use_future, use_awaitable, yield_context, or a function
                  object with the correct completion signature. The function signature
                  of the completion handler must be:
                
void handler( const asio::error_code& error, // Result of operation. std::size_t bytes_transferred // Number of bytes sent. );
                  Regardless of whether the asynchronous operation completes immediately
                  or not, the completion handler will not be invoked from within
                  this function. On immediate completion, invocation of the handler
                  will be performed in a manner equivalent to using post.
                
void(asio::error_code, std::size_t)
            On POSIX or Windows operating systems, this asynchronous operation supports
            cancellation for the following cancellation_type values:
          
cancellation_type::terminal
              cancellation_type::partial
              cancellation_type::total