code: func RegisterCrypt(c Crypt, f func() Crypter, prefix string) {
  	if c >= maxCrypt {
  		panic("crypt: RegisterHash of unknown crypt function")
  	}
  	crypts[c] = f
  	cryptPrefixes[c] = prefix
  }
docs: // RegisterCrypt registers a function that returns a new instance of the given
  // crypt function. This is intended to be called from the init function in
  // packages that implement crypt functions.