message: it is safe to call unwrap here as the value cannot be out of bound
  by design, the value cannot be greater than 2047. It is then safe to
  call `MnemonicIndex::new(v).unwrap()` here.
  relates to
diff: @@ -852,7 +852,14 @@ pub mod dictionary {
  None => {
  Err(Error::MnemonicWordNotFoundInDictionary(word.to_string()))
  },
  - Some(v) => Ok(MnemonicIndex::new(v as u16).unwrap())
  + Some(v) => {
  + Ok(
  + // it is safe to call unwrap as we guarantee that the
  + // returned index `v` won't be out of bound for a
  + // `MnemonicIndex` (DefaultDictionary.words is an array of 2048 elements)
  + MnemonicIndex::new(v as u16).unwrap()
  + )
  + }
  }
  }
  fn lookup_word(&self, mnemonic: MnemonicIndex) -> Result<String> {
  