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: layoutfmt.rs
    path of file: ./repos/ndarray/src/layout
    
    the code of the file until where you have to start completion: // Copyright 2017 bluss and ndarray developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use super::Layout;

cons
    
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if self.0 == 0 {
            write!(f, "Custom")?
        } else {
            (0..32).filter(|&i| self.is(1 << i)).try_fold((), |_, i| {
                if let Some(name) = LAYOUT_NAMES.get(i) {
                    write!(f, "{}", name)
                } else {
                    write!(f, "{:#x}", i)
                }
            })?;
        };
        write!(f, " ({:#x})", self.0)
    }