Title: Add .get(key) Function to Trie Class for Retrieving Values by Key

[colll78]

Description:

The current implementation of the Trie class supports insertion and deletion of values (.insert(key, value) and .delete(key)), but it lacks a straightforward method for retrieving a value by its key. Adding a .get(key) function would improve the usability of the library by providing an intuitive way to query the trie.

Proposed Implementation:

• Implement a .get(key) method in the Trie class that:
  1. Takes a key as input (either a Buffer or string).
  2. Navigates through the trie structure to locate the key.
  3. Returns the corresponding value if the key exists in the trie, or undefined if the key is not found.

/**
 * Retrieves the value at the given key from the Trie.
 *
 * @param {Buffer|string} key
 *   The key to search for. Strings are treated as UTF-8 byte buffers.
 * @returns {Promise<Buffer|undefined>}
 *   The value at the specified key, or `undefined` if the key is not found.
 */
async get(key) {
  // Convert the key into a path of nibbles
  const path = intoPath(key);

  // Use childAt to find the node corresponding to the path
  const node = await this.childAt(path);

  // If the node is a Leaf and the key matches, return the value
  if (node instanceof Leaf && node.key.equals(Buffer.from(key))) {
    return node.value;
  }

  // Return undefined if no matching node is found
  return undefined;
}

This addition will align with the existing .insert(key, value) and .delete(key) functions, making the API more complete and user-friendly.

Use Case Example:

const trie = await Trie.fromList([
  { key: 'foo', value: 'bar' },
  { key: 'baz', value: 'qux' }
]);

// Retrieve the value at key 'foo'
const value = await trie.get('foo');
console.log(value); // Expected output: 'bar'