code: func ConfigBlock(reader blockledger.Reader) *cb.Block {
  	lastBlock := blockledger.GetBlock(reader, reader.Height()-1)
  	index, err := utils.GetLastConfigIndexFromBlock(lastBlock)
  	if err != nil {
  		logger.Panicf("Chain did not have appropriately encoded last config in its latest block: %s", err)
  	}
  	configBlock := blockledger.GetBlock(reader, index)
  	if configBlock == nil {
  		logger.Panicf("Config block does not exist")
  	}
  
  	return configBlock
  }
docs: // ConfigBlock retrieves the last configuration block from the given ledger.
  // Panics on failure.