Function decode_utf16 

pub fn decode_utf16<I>(iter: I) -> DecodeUtf16<<I as IntoIterator>::IntoIter> 
where
    I: IntoIterator<Item = u16>,

👎Deprecating in a future version:

replaced by the decode_utf16 method on char

Creates an iterator over the UTF-16 encoded code points in iter, returning unpaired surrogates as Errs. Use char::decode_utf16 instead.