code: func (b *SimulatedBackend) AdjustTime(adjustment time.Duration) error {
  	b.mu.Lock()
  	defer b.mu.Unlock()
  	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(number int, block *core.BlockGen) {
  		for _, tx := range b.pendingBlock.Transactions() {
  			block.AddTx(tx)
  		}
  		block.OffsetTime(int64(adjustment.Seconds()))
  	})
  	statedb, _ := b.blockchain.State()
  
  	b.pendingBlock = blocks[0]
  	b.pendingState, _ = state.New(b.pendingBlock.Root(), statedb.Database())
  
  	return nil
  }
docs: // AdjustTime adds a time shift to the simulated clock.