code: func GetIdentityKey(s string) (*IdentityKey, error) {
  	if !IsValidIdentityKey(s) {
  		return nil, fmt.Errorf("invalid Identity Private Key")
  	}
  	p := base58.Decode(s)
  
  	if !bytes.Equal(p[:IDKeyPrefixLength], idSecPrefix) {
  		return nil, fmt.Errorf("invalid Identity Private Key")
  	}
  
  	return MakeIdentityKey(p[IDKeyPrefixLength:IDKeyBodyLength])
  }
docs: // GetIdentityKey takes a private key string and returns an IdentityKey.