$callback_groups instanceof WP_Hook ) {
				$normalized[ $hook_name ] = $callback_groups;
				continue;
			}

			$hook = new WP_Hook();

			// Loop through callback groups.
			foreach ( $callback_groups as $priority => $callbacks ) {

				// Loop through callbacks.
				foreach ( $callbacks as $cb ) {
					$hook->add_filter( $hook_name, $cb['function'], $priority, $cb['accepted_args'] );
				}
			}

			$normalized[ $hook_name ] = $hook;
		}

		return $normalized;
	}

	/**
	 * Determines whether an offset value exists.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/arrayaccess.offsetexists.php
	 *
	 * @param mixed $offset An offset to check for.
	 * @return bool True if the offset exists, false otherwise.
	 */
	#[ReturnTypeWillChange]
	public function offsetExists( $offset ) {
		return isset( $this->callbacks[ $offset ] );
	}

	/**
	 * Retrieves a value at a specified offset.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/arrayaccess.offsetget.php
	 *
	 * @param mixed $offset The offset to retrieve.
	 * @return mixed If set, the value at the specified offset, null otherwise.
	 */
	#[ReturnTypeWillChange]
	public function offsetGet( $offset ) {
		return isset( $this->callbacks[ $offset ] ) ? $this->callbacks[ $offset ] : null;
	}

	/**
	 * Sets a value at a specified offset.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/arrayaccess.offsetset.php
	 *
	 * @param mixed $offset The offset to assign the value to.
	 * @param mixed $value The value to set.
	 */
	#[ReturnTypeWillChange]
	public function offsetSet( $offset, $value ) {
		if ( is_null( $offset ) ) {
			$this->callbacks[] = $value;
		} else {
			$this->callbacks[ $offset ] = $value;
		}
	}

	/**
	 * Unsets a specified offset.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/arrayaccess.offsetunset.php
	 *
	 * @param mixed $offset The offset to unset.
	 */
	#[ReturnTypeWillChange]
	public function offsetUnset( $offset ) {
		unset( $this->callbacks[ $offset ] );
	}

	/**
	 * Returns the current element.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/iterator.current.php
	 *
	 * @return array Of callbacks at current priority.
	 */
	#[ReturnTypeWillChange]
	public function current() {
		return current( $this->callbacks );
	}

	/**
	 * Moves forward to the next element.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/iterator.next.php
	 *
	 * @return array Of callbacks at next priority.
	 */
	#[ReturnTypeWillChange]
	public function next() {
		return next( $this->callbacks );
	}

	/**
	 * Returns the key of the current element.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/iterator.key.php
	 *
	 * @return mixed Returns current priority on success, or NULL on failure
	 */
	#[ReturnTypeWillChange]
	public function key() {
		return key( $this->callbacks );
	}

	/**
	 * Checks if current position is valid.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/iterator.valid.php
	 *
	 * @return bool Whether the current position is valid.
	 */
	#[ReturnTypeWillChange]
	public function valid() {
		return key( $this->callbacks ) !== null;
	}

	/**
	 * Rewinds the Iterator to the first element.
	 *
	 * @since 4.7.0
	 *
	 * @link https://www.php.net/manual/en/iterator.rewind.php
	 */
	#[ReturnTypeWillChange]
	public function rewind() {
		reset( $this->callbacks );
	}

}