Constructors

Unlike other programming languages, Rust doesn't have a build-in constructor keyword to construct instances of a struct. Instead, you can directly create an instance of a struct simply by calling the struct's name and passing the required values.

struct Post {
    pub content: String,
    pub user: String,
    pub views: u32
}
 
fn main(){
    let new_blog_post = Post {
        content: "Some content".to_string(),
        user: "Jon Doe".to_string(),
        views: 0
    };
}

However, this pattern is discouraged, in real-life scenarios, we might not want to expose all fields with pub or some fields will have default values that it would be repetitive to provide the value for every new instance, instead.

In Rust we have a convention, constructors are implemented as associated functions named new. They encapsulate the initialization of the struct, ensuring that instances are always created in a valid state.

For example, for the Post struct above, we can have a default value for the views to always be 0 for new instances.

impl Post {
    pub fn new(content: String, user: String) -> Post {
        Post {
            content,
            user,
            views: 0
        }
    }
}
 
fn main(){
    let new_blog_post = Post::new(
        "Some content".to_string(),
        "Jon Doe".to_string()
    );
}

Your Task

In this challenge, you will implement a constructor for a struct that represents a Book. A Book will have the following fields:

title: A string that represents the book's title.
author: A string that represents the book's author.
year: An integer that represents the year the book was published.
likes: An integer that represents the number of likes the book has received. Default value is 0.

The constructor function, Book::new, should take three parameters (title, author, and year) and return a fully initialized Book.

Requirements

Implement a constructor function Book::new that:
- Takes three arguments: title: &str, author: &str, and year (integer).
- Returns a Book instance with the specified values and default likes value of 0.
Remember to use pub for fields (required for testing).

Example Test

let book = Book::new(
    "ASOIAF",
    "George R. R. Martin",
    1996
);
 
assert_eq!(book.title, "ASOIAF");
assert_eq!(book.author, "George R. R. Martin");
assert_eq!(book.year, 1996);
assert_eq!(book.likes, 0);

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Solutions

buu

bushuai

3 minutes ago

3.68ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

buu

bushuai

4 minutes ago

3.52ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: isize,
    pub likes: usize,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: isize) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

iamforgettable

2 hours ago

5.38ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i16,
    pub likes: i32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i16) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

Taufik Hidayat

tfkhdyt

6 hours ago

3.81ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Levent Can Yılmaz

lvntcnylmz

11 hours ago

4.54ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self{
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Nikita Smirnov

Nismirno

12 hours ago

4.38ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: String::from(title),
            author: String::from(author),
            year,
            likes: 0,
        }
    }
}

エヴァンゲリオン

Lu-zihang

21 hours ago

4.36ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        return Book {
            title: String::from(title),
            author: String::from(author),
            year,
            likes: 0
        };
    }
}

Viktor Merkurev

fennr

21 hours ago

4.41ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0,
        }
    }
}

Illus1on

hjklchan

a day ago

10.20ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u64,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_owned(),
            author: author.to_owned(),
            year,
            likes: 0,
        }
    }
}

Kentaro Abe

abekem

a day ago

4.82ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Elliott Draper

ejdraper

a day ago

4.27ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        return Book {
            title: String::from(title),
            author: String::from(author),
            year,
            likes: 0
        };
    }
}

Stefan Roas

sroas

2 days ago

4.87ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub year: i32,
    pub likes: i32,
    pub title: String,
    pub author: String,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Algorab

2 days ago

4.78ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

sander-b-postnl

2 days ago

4.68ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

kosay

sarub0b0

2 days ago

6.16ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i64,
    pub likes: u64,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i64) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Jim Lawton

jimlawton

2 days ago

8.63ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Denis SOURON

Brack0

2 days ago

4.31ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

medzernik

2 days ago

3.83ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i64,
    pub likes: i64
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
}
impl Book {
    pub fn new(title: &str, author: &str, year: i64) -> Self {
        Self {title: title.to_string(), author: author.to_string(), year, likes: 0}
    }
    // 2. Define the `new` associated function
}

kada-s

sy34

2 days ago

22.87ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

dcodes

dcodesdev

2 days ago

4.16ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

Suresh Prajapati

toddlers

3 days ago

4.02ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year:i32)-> Self {
        Book{
            title:title.to_string(),
            author:author.to_string(),
            year:year,
            likes:0
        }
    }
}

Jeroen Rooijmans

jeroen-rooijmans

3 days ago

4.42ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

B L I

blietaer

3 days ago

5.21ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,    
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title : title.to_string(),
            author : author.to_string(),
            year : year, 
            likes: 0,
        }
    }
}

Diego Maia

diegocmsantos

3 days ago

4.69ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Mohammed Omar Miraj

MOmarMiraj

3 days ago

5.33ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i16,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i16) -> Self {
        Self{
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

TaiPoole

3 days ago

4.38ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {title: title.to_string(), author: author.to_string(), year, likes: 0}
    }
}

r1kk1s

4 days ago

4.24ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u8,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

michdorf

4 days ago

3.81ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields 
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(), 
            author: author.to_string(),
            year, 
            likes: 0
        }
    }
}

Jonathan Voss

jvoss

4 days ago

6.62ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i16,
    pub likes: u32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i16) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

roux g. buciu

adudenamedruby

4 days ago

4.22ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

Sakura

sakkura

4 days ago

4.46ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

dawwestk

4 days ago

7.62ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0
        }
    }
}

Romain Grimau

Herrgrim0

5 days ago

3.92ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

delxs

5 days ago

4.23ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i16,
    pub likes: u16,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i16) -> Book {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0,
        }
    }
}

Benjamin Falk

lumio

5 days ago

3.95ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0,
        }
    }
}

tzmijewski

5 days ago

3.74ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0
        }
    }
}

Marco-Normal

5 days ago

4.18ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.into(),
            author: author.into(),
            year,
            likes: 0
        }
    }
}

rawar089

5 days ago

3.68ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book { title: title.to_string(), 
               author: author.to_string(), 
               year, 
               likes: 0}
    }
}

Todsaporn Banjerdkit

katopz

5 days ago

4.20ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new (title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_owned(),
            author: author.to_owned(),
            year,
            likes: 0u32,
        }
    }
}

Shafer Hess

shafer-hess

5 days ago

4.79ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0
        }
    }
}

Oebelus

oebelus

5 days ago

4.29ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}

Christopher Nielson

c-nielson

5 days ago

3.78ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book{title: title.to_string(), author: author.to_string(), year, likes: 0}
    }
}

tzmijewski

6 days ago

9.19ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0
        }
    }
}

Suraj Vijayan

its-me-sv

6 days ago

4.21ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: impl Into<String>, author: impl Into<String>, year: i32) -> Book {
        Self {
            title: title.into(),
            author: author.into(),
            year,
            likes: 0,
        }
    }
}

Tboot

tboot-0510

6 days ago

4.74ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        Book {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes:0,
        }
    }
}

Simon Noetzlin

sainoe

6 days ago

3.94ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Book{
       Book{
          title: title.to_string(),
          author: author.to_string(),
          year,
          likes : 0,
       }
    }
}

moo-9523

6 days ago

4.61ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Book {
        return Book {
            title: title.to_string(),
            author: author.to_string(),
            year: year,
            likes: 0
        }
    }
}

zahrajavar

6 days ago

5.63ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: i32,
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self{
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes:0,
        }
    }
    // 2. Define the `new` associated function
}

Justin Maillet

justy777

7 days ago

6.27ms

89.32kb

pub struct Book {
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.into(), 
            author: author.into(), 
            year, 
            likes: 0}
    }
}

Tengz Mao

MaoX-Yu

7 days ago

5.13ms

89.32kb

pub struct Book {
    // 1. Define the fields of the struct
    // Make all of them public with `pub`
    // Read the description for the fields
    pub title: String,
    pub author: String,
    pub year: i32,
    pub likes: u32,
}
impl Book {
    // 2. Define the `new` associated function
    pub fn new(title: &str, author: &str, year: i32) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            year,
            likes: 0,
        }
    }
}