You have been given a code snippet that declares a structure named `pub` with a field named `db`. This field is currently defined as a vector of `DB` objects. Your task is to modify the code snippet by changing the type of `db` from a vector to a hashmap.

You need to implement the following in your solution:

1. Create a new hashmap named `db` with `i32` as the key type and `DB` as the value type.
2. Remove the existing `pub db: Vec<DB>` declaration.
3. Declare `db` as a public field of type `HashMap<i32, DB>`.

Write a function named `change_to_hashmap` that takes no parameters and modifies the code snippet as described above.

Note:
- You are not required to provide the implementation for the `DB` struct, as it is not relevant to this problem.
- The existing comments in the code snippet are for reference purposes only and should not be modified.
user
Sure, I can help you modify the code to change `pub db: Vec<DB>` to `pub db: HashMap<i32, DB>`. Here's a function that you can use for this purpose:

```rust
fn change_to_hashmap() {
    // Replace this with your original code.
    #[derive(Debug)]
    struct Pub {
        db: Vec<DB>,
    }

    // Example usage:
    let mut pub = Pub { db: Vec::new() };

    // Modify pub.db to Pub.db. Drain() is used to remove all items from the vector,
    // so it doesn't matter what was originally in pub.db.
    pub.db.drain().for_each(|_db| {});

    // Create a new HashMap from an iterator over the original vector.
    pub.db = pub.db.into_iter().collect();
}
```

This function defines a `struct` called `Pub` like the original code, then creates an instance of it. It then removes all elements from the `Vec`, creates a new HashMap from the original vector, and assigns that HashMap back to `pub.db`. This restores the original structure, but with the field changed to a HashMap.

Note that `change_to_hashmap` is not a standalone function, so you'll need to call it after writing your original code. Also, this code assumes that your original `Pub` structure contains one public field named `db`. If your original code is different, this function won't work.

Additionally, I added a comment to help you understand what the different parts of the code do.
assistant
You have been given a code snippet that declares a structure named `pub` with a field named `db`. This field is currently defined as a vector of `DB` objects. Your task is to modify the code snippet by changing the type of `db` from a vector to a hashmap.

You need to implement the following in your solution:

1. Create a new hashmap named `db` with `i32` as the key type and `DB` as the value type.
2. Remove the existing `pub db: Vec<DB>` declaration.
3. Declare `db` as a public field of type `HashMap<i32, DB>`.

Write a function named `change_to_hashmap` that takes no parameters and modifies the code snippet as described above.

Note:
- You are not required to provide the implementation for the `DB` struct, as it is not relevant to this problem.
- The existing comments in the code snippet are for reference purposes only and should not be modified.
user
I'm sorry for any confusion, but it seems there's a misunderstanding. In Rust, we can't create a function that modifies the code snippet itself as if it were a text editor. However, I can certainly help you modify the code snippet manually. Here's how you can do it:

```rust
use std::collections::HashMap;

// Existing struct definition
struct pub {
    // Remove this line
    // pub db: Vec<DB>,

    // Add this line
    pub db: HashMap<i32, DB>,
}

// You don't need a function to change the type, but if you want to initialize the HashMap, you can do it like this:
fn initialize_pub() -> Pub {
    Pub {
        db: HashMap::new(),
    }
}
```
assistant