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: mod.rs
    path of file: ./repos/kcl/compiler_base/error/src/diagnostic
    
    the code of the file until where you have to start completion: use crate::errors::ComponentFormatError;
pub use rustc_errors::styled_buffer::{StyledBuffer, StyledString};
use rustc_errors::Style;
use std::fmt::Debug;

pub mod components;
pub mod diagnostic_handler;
pub mod diagnostic_message;
pub mod style;

#[cfg(test)]
mod tests;

/// 'Component' specifies the m
    
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut diag_fmt = String::new();
        for component in &self.components {
            let mut s_sb = StyledBuffer::<T>::new();
            let mut s_errs = vec![];
            component.format(&mut s_sb, &mut s_errs);
            diag_fmt.push_str(&format!("{:?}\n", s_sb.render()));
        }
        write!(f, "{}", diag_fmt)
    }