impl<'de> Visitor<'de> for EncodingVisitor {
    type Value = Encoding;
    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        formatter.write_str("a string label meeting the encoding standard https://encoding.spec.whatwg.org/#concept-encoding-get")
    }
    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
    where
        E: serde::de::Error,
    {
        Ok(Encoding::for_label(v))
    }
}

        impl<'de> Visitor<'de> for EncodingVisitor {
            type Value = Encoding;
            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
                formatter.write_str("a string label meeting the encoding standard https://encoding.spec.whatwg.org/#concept-encoding-get")
            }
            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
            where
                E: serde::de::Error,
            {
                Ok(Encoding::for_label(v))
            }
        }