code: def pipe_to_process(self, payload):
          
          message = payload['input']
          key = payload['key']
          if not self.process_handler.is_running(key):
              return {'message': 'No running process for this key',
                      'status': 'error'}
          self.process_handler.send_to_process(message, key)
          return {'message': 'Message sent',
                  'status': 'success'}
docs: Send something to stdin of a specific process.