code: func NewFakeDelayer(delay time.Duration) *Ethash {
  	return &Ethash{
  		config: Config{
  			PowMode: ModeFake,
  		},
  		fakeDelay: delay,
  	}
  }
docs: // NewFakeDelayer creates a ethash consensus engine with a fake PoW scheme that
  // accepts all blocks as valid, but delays verifications by some time, though
  // they still have to conform to the Ethereum consensus rules.