code: async function requireTransferHelper(){
      // hex write helper already uploaded within current session ?
      // otherwise upload helper
      if (_isTransferWriteHelperUploaded !== true){
          let response = null;
  
          try{
              ({response} = await _virtualTerminal.executeCommand(_luaCommandBuilder.command.transferWriteHelper));
  
          }catch(e){
              _logger.debug(e);
              throw new Error('cannot upload transfer helper function');
          }
  
          // get transfer encoding
          if (response == 'b'){
              _transferEncoding = 'base64'
          }else if (response == 'h'){
              _transferEncoding = 'hex'
          }else{
              throw new Error('unknown transfer encoding - ' + response);
          }
  
          // show encoding
          _logger.log('Transfer-Mode: ' + _transferEncoding);
  
          // set flag
          _isTransferWriteHelperUploaded = true;
      }
  }
docs: utility function to upload file transfer helper