You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: unserializers.rs
    path of file: ./repos/teloxide/crates/teloxide-core/src/serde_multipart
    
    the code of the file until where you have to start completion: mod bytes;
mod input_file;
mod string;

pub(crate) use input_file::InputFileUnserializer;
pub(crate) use string::StringUnserializer;

use std::fmt::{self, Display};

use serde::ser;

#[derive(Debug, PartialEq, Eq)]
pub enum UnserializerError {
    Custom(String),
    UnsupportedType {
        ty: &'static str,
        supported: &'static str,
    },
    UnexpectedField {
        name: &'static str,
        expected: &'static [&'static str],
    },
    UnexpectedVariant {
        name: &'static str,
        expected: &'static [&'static str],
    },
    WrongLen {
        len: usize,
        expected: usize,
    },
}

impl ser::Error for UnserializerError {
    fn custom<T>(msg: T) -> Self
    where
        T: Display,
    {
        Self::Custom(msg.to_string())
    }
}

impl Display for UnserializerError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self 
    
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::UnexpectedField { name, expected } => write!(
                f,
                "Unexpected field: `{}`, expected field(s): `{}`",
                name,
                expected.join(", ")
            ),
            Self::Custom(s) => write!(f, "Custom serde error: {}", s),
            Self::UnsupportedType { ty, supported } => {
                write!(
                    f,
                    "Unsupported type: `{}`, supported type(s): `{}`",
                    ty, supported
                )
            }
            Self::UnexpectedVariant { name, expected } => write!(
                f,
                "Unexpected variant: `{}`, expected variants(s): `{}`",
                name,
                expected.join(", ")
            ),
            Self::WrongLen { len, expected } => {
                write!(f, "Wrong len: `{}`, expected `{}`", len, expected)
            }
        }
    }