message: more comments format
diff: @@ -250,7 +250,8 @@ impl<T: IdType> Id<T> {
  /// - `IdError::InvalidId` - if `id` contains non-alphanumeric characters.
  pub fn from_id<'a, 'b: 'a>(id: &'b str) -> Result<&'a Id<T>, IdError> {
  if id.chars().all(|ch| ch.is_ascii_alphanumeric()) {
  - // Safe, b/c Id is just a str with ZST type tag, and id is proved to be a valid id at this point
  + // Safe, b/c Id is just a str with ZST type tag, and id is proved
  + // to be a valid id at this point
  Ok(unsafe { &*(id as *const str as *const Id<T>) })
  } else {
  Err(IdError::InvalidId)
  