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: segment.rs
    path of file: ./repos/grin/core/tests
    
    the code of the file until where you have to start completion: // Copyright 2021 The Grin Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, sof
    
fn test_unprunable_size(height: u8, n_leaves: u32) {
	let size = 1u64 << height;
	let n_segments = (n_leaves as u64 + size - 1) / size;

	// Build an MMR with n_leaves leaves
	let mut ba = pmmr::VecBackend::new();
	let mut mmr = pmmr::PMMR::new(&mut ba);
	for i in 0..n_leaves {
		mmr.push(&TestElem([i / 7, i / 5, i / 3, i])).unwrap();
	}
	let mmr = mmr.readonly_pmmr();
	let last_pos = mmr.unpruned_size();
	let root = mmr.root().unwrap();

	for idx in 0..n_segments {
		let id = SegmentIdentifier { height, idx };
		let segment = Segment::from_pmmr(id, &mmr, false).unwrap();
		println!(
			"\n\n>>>>>>> N_LEAVES = {}, LAST_POS = {}, SEGMENT = {}:\n{:#?}",
			n_leaves, last_pos, idx, segment
		);
		if idx < n_segments - 1 || (n_leaves as u64) % size == 0 {
			// Check if the reconstructed subtree root matches with the hash stored in the mmr
			let subtree_root = segment.root(last_pos, None).unwrap().unwrap();
			let last = pmmr::insertion_to_pmmr_index((idx + 1) * size - 1) + (height as u64);
			assert_eq!(subtree_root, mmr.get_hash(last).unwrap());
			println!(" ROOT OK");
		}
		segment.validate(last_pos, None, root).unwrap();
		println!(" PROOF OK");
	}
}