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    use lib::*;
    use ser::{Error, Impossible, Serialize, Serializer};

    impl Error for fmt::Error {
        fn custom<T: Display>(_msg: T) -> Self {
            fmt::Error
        }
    }

    macro_rules! fmt_primitives {
        ($($f:ident: $t:ty,)*) => {
            $(
                fn $f(self, v: $t) -> fmt::Result {
                    Display::fmt(&v, self)
                }
            )*
        };
    }

    /// ```edition2018
    /// use serde::Serialize;
    /// use std::fmt::{self, Display};
    ///
    /// #[derive(Serialize)]
    /// #[serde(rename_all = "kebab-case")]
    /// pub enum MessageType {
    ///     StartRequest,
    ///     EndRequest,
    /// }
    ///
    /// impl Display for MessageType {
    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    ///         self.serialize(f)
    ///     }
    /// }
    /// ```
    impl<'a, 'b> Serializer for &'a mut fmt::Formatter<'b> {
        type Ok = ();
        type Error = fmt::Error;
        type SerializeSeq = Impossible<(), fmt::Error>;
        type SerializeTuple = Impossible<(), fmt::Error>;
        type SerializeTupleStruct = Impossible<(), fmt::Error>;
        type SerializeTupleVariant = Impossible<(), fmt::Error>;
        type SerializeMap = Impossible<(), fmt::Error>;
        type SerializeStruct = Impossible<(), fmt::Error>;
        type SerializeStructVariant = Impossible<(), fmt::Error>;

        fmt_primitives! {
            serialize_bool: bool,
            serialize_i8: i8,
            serialize_i16: i16,
            serialize_i32: i32,
            serialize_i64: i64,
            serialize_u8: u8,
            serialize_u16: u16,
            serialize_u32: u32,
            serialize_u64: u64,
            serialize_f32: f32,
            serialize_f64: f64,
            serialize_char: char,
            serialize_str: &str,
            serialize_unit_struct: &'static str,
        }

        serde_if_integer128! {
            fmt_primitives! {
                serialize_i128: i128,
                serialize_u128: u128,
            }
        }

        fn serialize_unit_variant(
            self,
            _name: &'static str,
            _variant_index: u32,
            variant: &'static str,
        ) -> fmt::Result {
            Display::fmt(variant, self)
        }

        fn serialize_newtype_struct<T: ?Sized>(self, _name: &'static str, value: &T) -> fmt::Result
        where
            T: Serialize,
        {
            Serialize::serialize(value, self)
        }

        fn serialize_bytes(self, _v: &[u8]) -> fmt::Result {
            Err(fmt::Error)
        }

        fn serialize_none(self) -> fmt::Result {
            Err(fmt::Error)
        }

        fn serialize_some<T: ?Sized>(self, _value: &T) -> fmt::Result
        where
            T: Serialize,
        {
            Err(fmt::Error)
        }

        fn serialize_unit(self) -> fmt::Result {
            Err(fmt::Error)
        }

        fn serialize_newtype_variant<T: ?Sized>(
            self,
            _name: &'static str,
            _variant_index: u32,
            _variant: &'static str,
            _value: &T,
        ) -> fmt::Result
        where
            T: Serialize,
        {
            Err(fmt::Error)
        }

        fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, fmt::Error> {
            Err(fmt::Error)
        }

        fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple, fmt::Error> {
            Err(fmt::Error)
        }

        fn serialize_tuple_struct(
            self,
            _name: &'static str,
            _len: usize,
        ) -> Result<Self::SerializeTupleStruct, fmt::Error> {
            Err(fmt::Error)
        }

        fn serialize_tuple_variant(
            self,
            _name: &'static str,
            _variant_index: u32,
            _variant: &'static str,
            _len: usize,
        ) -> Result<Self::SerializeTupleVariant, fmt::Error> {
            Err(fmt::Error)
        }

        fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, fmt::Error> {
            Err(fmt::Error)
        }

        fn serialize_struct(
            self,
            _name: &'static str,
            _len: usize,
        ) -> Result<Self::SerializeStruct, fmt::Error> {
            Err(fmt::Error)
        }

        fn serialize_struct_variant(
            self,
            _name: &'static str,
            _variant_index: u32,
            _variant: &'static str,
            _len: usize,
        ) -> Result<Self::SerializeStructVariant, fmt::Error> {
            Err(fmt::Error)
        }

        fn collect_str<T: ?Sized>(self, value: &T) -> fmt::Result
        where
            T: Display,
        {
            Display::fmt(value, self)
        }
    }