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: token.rs
    path of file: ./repos/pomsky/pomsky-syntax/src/lexer
    
    the code of the file until where you have to start completion: use super::LexErrorMsg;

/// A token encountered while lexing a pomsky expression.
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
#[non_exhaustive]
pub enum Token {
    /// `^` (start boundary)
    Caret,
    /// `$` (end boundary)
    Dollar,
    /// `%` (`\b` boundary)
    BWord,

    /// `*` (`*?` repetition)
    Star,
    /// `+` (`+?` repetition)
    Plus,
    /// `?` (`??` repetition)
    QuestionMark,

    /// `|` (or)
    Pipe,

    /// `:` (capturing group start)
    Colon,
    /// `(` (open group)
    OpenParen,
    /// `)` (close group)
    CloseParen,

    /// `{` (open repetition)
    OpenBrace,
    /// `}` (close repetition)
    CloseBrace,
    /// `,` (comma in repetition)
    Comma,

    /// `!` (negation)
    Not,

    /// `[` (open character class)
    OpenBracket,

    /// `-` (unicode range)
    Dash,

    /// `]` (close character class)
    CloseBracket,

    /// `.` (any code point except newline)
    Dot,

    /// `>>` (positive lookahead)
    LookAhead,

    /// `<<` (pos
    
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(match self {
            Token::Caret => "`^`",
            Token::Dollar => "`$`",
            Token::BWord => "`%`",
            Token::Star => "`*`",
            Token::Plus => "`+`",
            Token::QuestionMark => "`?`",
            Token::Pipe => "`|`",
            Token::Colon => "`:`",
            Token::OpenParen => "`(`",
            Token::CloseParen => "`)`",
            Token::OpenBrace => "`{`",
            Token::CloseBrace => "`}`",
            Token::Comma => "`,`",
            Token::LookAhead => "`>>`",
            Token::LookBehind => "`<<`",
            Token::AngleLeft => "`<`",
            Token::AngleRight => "`>`",
            Token::DoubleColon => "`::`",
            Token::Not => "`!`",
            Token::OpenBracket => "`[`",
            Token::Dash => "`-`",
            Token::CloseBracket => "`]`",
            Token::Dot => "`.`",
            Token::Semicolon => "`;`",
            Token::Equals => "`=`",
            Token::String => "string",
            Token::CodePoint => "code point",
            Token::Number => "number",
            Token::Identifier => "identifier",
            Token::ReservedName => "reserved name",
            Token::ErrorMsg(_) | Token::Error => "error",
        })
    }