|  | 
           
(Deprecated: Use dispatch.)
          Request the io_context
          to invoke the given handler.
        
template< typename LegacyCompletionHandler> auto dispatch( LegacyCompletionHandler && handler);
          This function is used to ask the io_context to execute the given
          handler.
        
          The io_context
          guarantees that the handler will only be called in a thread in which the
          run(),
          run_one(),
          poll()
          or poll_one()
          member functions is currently being invoked. The handler may be executed
          inside this function if the guarantee can be met.
        
                The handler to be called. The io_context will make a copy
                of the handler object as required. The function signature of the
                handler must be:
              
void handler();
This function throws an exception only if:
throws an exception.