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: tokenizer.rs
    path of file: ./repos/fastn/fastn-expr/src
    
    the code of the file until where you have to start completion: #[derive(thiserror::Error, Debug, PartialEq)]
pub enum TokenizerError {
    #[error("Unexpected token '{token}' at position {position}")]
    UnexpectedToken { token: char, position: usize },
    #[error("String left open at position {position}")]
    StringLeftOpen { position: usize },
}

#[derive(Debug, PartialEq, Clone)]
pub enum Token {
    Identifier(String),
    Operator(Operator),
    StringLiteral(String),
    Integer(i64),
    Decimal(f64),
}

#[derive(Debug, PartialEq, Clone)]
pub enum Operator {
    Or,
}

pub fn tokenize(input: &str) -> Result<Vec<Token>, TokenizerError> {
 
    
fn test_expr() {
    assert_eq!(
        tokenize(r#"env.ENDPOINT or "127.0.0.1:8000""#).unwrap(),
        vec![
            Token::Identifier(String::from("env.ENDPOINT")),
            Token::Operator(Operator::Or),
            Token::StringLiteral(String::from("127.0.0.1:8000"))
        ]
    );
    assert_eq!(
        tokenize(r#"env.FT_ENDPOINT or "or 127.0.0.1:8000""#).unwrap(),
        vec![
            Token::Identifier(String::from("env.FT_ENDPOINT")),
            Token::Operator(Operator::Or),
            Token::StringLiteral(String::from("or 127.0.0.1:8000"))
        ]
    );
    assert_eq!(tokenize(r#"-100"#).unwrap(), vec![Token::Integer(-100)]);
    assert_eq!(
        tokenize(r#""This is a \" inside a string literal""#).unwrap(),
        vec![Token::StringLiteral(String::from(
            r#"This is a " inside a string literal"#
        ))]
    );
    assert_eq!(
        tokenize(r#""This is a \\" inside a string literal""#).unwrap_err(),
        TokenizerError::StringLeftOpen { position: 39 }
    );
    assert_eq!(
        tokenize(r#""This is string that was left open"#).unwrap_err(),
        TokenizerError::StringLeftOpen { position: 34 }
    );
}