code: def _send_command_to_servers(self, head, body):
          
          check_call(_LIB.MXKVStoreSendCommmandToServers(
              self.handle, mx_uint(head), c_str(body)))
docs: Sends a command to all server nodes.
  
          Sending command to a server node will cause that server node to invoke
          ``KVStoreServer.controller`` to execute the command.
  
          This function returns after the command has been executed on all server
          nodes.
  
          Parameters
          ----------
          head : int
              the head of the command.
          body : str
              the body of the command.