diff --git a/examples/sst-demo.rs b/examples/sst-demo.rs
index 37cd88e..de1c63c 100644
--- a/examples/sst-demo.rs
+++ b/examples/sst-demo.rs
@@ -38,12 +38,6 @@ impl fmt::Display for DemoError {
 
 impl Error for DemoError {}
 
-impl DemoError {
-    pub fn raise<R>(message: String) -> Result<R, Box<dyn Error>> {
-        Err(Box::new(Self(message)))
-    }
-}
-
 type Hasher = Sha256_192;
 
 struct GenKeyParameter {
@@ -154,12 +148,8 @@ fn sign(args: &ArgMatches) -> Result<(), std::io::Error> {
         .try_into()
         .unwrap_or_else(|_| panic!("Tree identifier has wrong length"));
 
-    let mut private_key_update_function = |new_key: &[u8]| {
-        if write(&private_key_filename, new_key).is_ok() {
-            return Ok(());
-        }
-        Err(())
-    };
+    let mut private_key_update_function =
+        |new_key: &[u8]| write(&private_key_filename, new_key).map_err(|_| ());
 
     let signature = hbs_lms::sign::<Hasher>(
         &message_data,
@@ -187,12 +177,10 @@ fn verify(args: &ArgMatches) -> bool {
     hbs_lms::verify::<Hasher>(&message_data, &signature_data, &public_key_data).is_ok()
 }
 
-fn get_filename(keyname: &str, idx: Option<u8>, suffix: &str) -> String {
-    if let Some(idx) = idx {
-        format!("{}.{}.{}", keyname, &idx, suffix)
-    } else {
-        format!("{}.{}", keyname, suffix)
-    }
+fn get_filename(filename: &str, idx: Option<u8>, suffix: &str) -> String {
+    idx.map_or(format!("{}.{}", filename, suffix), |idx| {
+        format!("{}.{}.{}", filename, &idx, suffix)
+    })
 }
 
 fn get_public_key_filename(keyname: &str, idx: Option<u8>) -> String {
@@ -236,8 +224,7 @@ fn prepare_keygen(args: &ArgMatches) -> Result<(), Box<dyn std::error::Error>> {
     let arg_init_tree_ident = args.get_flag(ARG_INIT_TREE_IDENT);
     let treeident_filename = get_treeident_filename(&keyname);
     let mut tree_identifier = if !arg_init_tree_ident {
-        let tree_ident_filedata = read_file(&treeident_filename);
-        tree_ident_filedata
+        read_file(&treeident_filename)
             .try_into()
             .unwrap_or_else(|_| panic!("Tree identifier has wrong length"))
     } else {
@@ -249,33 +236,28 @@ fn prepare_keygen(args: &ArgMatches) -> Result<(), Box<dyn std::error::Error>> {
         &get_parameter(ARG_SSTS_PARAM, args),
         &get_parameter(ARG_AUXSIZE, args),
     );
-
-    let hss_parameters = genkey_parameter.hss_parameters;
     let sst_extension = genkey_parameter.sst_extension;
 
-    let seed: Seed<Hasher> = if let Some(seed) = args.value_of(ARG_SEED) {
-        let decoded = hex::decode(seed)?;
-        if decoded.len() != Hasher::OUTPUT_SIZE as usize {
-            let error = format!(
-                "Seed is too short ({} of {} required bytes)",
-                decoded.len(),
-                Hasher::OUTPUT_SIZE
-            );
-            return DemoError::raise(error);
-        }
-        let mut seed = Seed::default();
-        seed.as_mut_slice().copy_from_slice(&decoded[..]);
-        seed
-    } else {
-        return DemoError::raise("Seed was not given".to_string());
-    };
+    let encoded_seed = args
+        .value_of(ARG_SEED)
+        .ok_or(DemoError("No seed given".to_string()))?;
+    let decoded_seed = hex::decode(encoded_seed)?;
+    (decoded_seed.len() == Hasher::OUTPUT_SIZE.into())
+        .then_some(())
+        .ok_or(DemoError(format!(
+            "Seed length is {} bytes, but length of {} bytes is expected",
+            decoded_seed.len(),
+            Hasher::OUTPUT_SIZE
+        )))?;
+    let mut seed = Seed::<Hasher>::default();
+    seed.as_mut_slice().copy_from_slice(&decoded_seed[..]);
 
     let mut aux_data = vec![0u8; genkey_parameter.aux_data];
     let aux_slice: &mut &mut [u8] = &mut &mut aux_data[..];
 
     // create our private key
     let (signing_key, intermed_node_hashval) = prepare_sst_keygen(
-        &hss_parameters,
+        &genkey_parameter.hss_parameters,
         &sst_extension,
         &seed,
         Some(aux_slice),