code: func GetFactoidAddress(s string) (*FactoidAddress, error) {
  	if !IsValidAddress(s) {
  		return nil, fmt.Errorf("Invalid Address")
  	}
  
  	p := base58.Decode(s)
  
  	if !bytes.Equal(p[:PrefixLength], fcSecPrefix) {
  		return nil, fmt.Errorf("Invalid Factoid Private Address")
  	}
  
  	return MakeFactoidAddress(p[PrefixLength:BodyLength])
  }
docs: // GetFactoidAddress takes a private address string (Fs...) and returns a
  // FactoidAddress.