code: func NewFakeFailer(fail uint64) *Ethash {
  	return &Ethash{
  		config: Config{
  			PowMode: ModeFake,
  		},
  		fakeFail: fail,
  	}
  }
docs: // NewFakeFailer creates a ethash consensus engine with a fake PoW scheme that
  // accepts all blocks as valid apart from the single one specified, though they
  // still have to conform to the Ethereum consensus rules.