code: func GetProofOfWorkImpl(name string) (ProofOfWorkFunc, error) {
  	if p, exist := proofOfWorkFuncs[name]; exist {
  		return p, nil
  	}
  
  	return nil, errors.Wrapf(ErrUnknownProofOfWorkFunc, "%s", name)
  }
docs: // GetProofOfWorkImpl returns the specified Proof-of-Work implementation given a name.