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: tree_builder.rs
    path of file: ./repos/tools/crates/rome_rowan/src
    
    the code of the file until where you have to start completion: use crate::{
    cow_mut::CowMut,
    green::{GreenElement, NodeCache, NodeCacheNodeEntryMut},
    syntax::TriviaPiece,
    GreenNode, Language, NodeOrToken, ParsedChildren, SyntaxFactory, SyntaxKind, SyntaxNode,
};
use std::marker::PhantomData;

/// A checkpoint for maybe wrapping a node. See `GreenNodeBuilder::checkpoint` for details.
#[derive(Clone, Copy, Debug)]
pub struct Checkpoint(usize);

/// A builder for a syntax tree.
#[derive(Debug)]
pub struct TreeBuilder<'cache, L: Language, S: SyntaxFactory<Kind = L::Kind>> {
    cache: CowMut<'cache, NodeCache>,
    parents: Vec<(L::Kind, usize)>,
    children: Vec<(u64, GreenElement)>,
    ph: PhantomData<S>,
}

impl<L: Language
    
    fn doesnt_cache_node_if_empty_slots_differ() {
        let mut builder = RawSyntaxTreeBuilder::new();

        builder.start_node(RawLanguageKind::ROOT); // Root
        build_condition_with_missing_closing_parenthesis(&mut builder); // misses the ')'

        // Create a well formed condition
        builder.start_node(RawLanguageKind::CONDITION);

        builder.token(RawLanguageKind::L_PAREN_TOKEN, "(");

        builder.start_node(RawLanguageKind::LITERAL_EXPRESSION);
        builder.token(RawLanguageKind::STRING_TOKEN, "a");
        builder.finish_node();

        // missing )
        builder.token(RawLanguageKind::R_PAREN_TOKEN, ")");

        builder.finish_node();

        // finish root
        builder.finish_node();

        let root = builder.finish_green();
        let first_condition = root.children().next().unwrap();
        let last_condition = root.children().last().unwrap();

        assert_ne!(first_condition.element(), last_condition.element());
    }