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: lib.rs
    path of file: ./repos/polkadot/node/network/bitfield-distribution/src
    
    the code of the file until where you have to start completion: // Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.

// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Polkadot is distributed in the hope that i
    
fn handle_our_view_change(state: &mut ProtocolState, view: OurView) {
	let old_view = std::mem::replace(&mut (state.view), view);

	for added in state.view.difference(&old_view) {
		if !state.per_relay_parent.contains_key(&added) {
			// Is guaranteed to be handled in `ActiveHead` update
			// so this should never happen.
			gum::error!(
				target: LOG_TARGET,
				%added,
				"Our view contains {}, but not in active heads",
				&added
			);
		}
	}
	for removed in old_view.difference(&state.view) {
		// cleanup relay parents we are not interested in any more
		let _ = state.per_relay_parent.remove(&removed);
	}
}