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: reader.rs
    path of file: ./repos/lnx/lnx-engine/search-index/src
    
    the code of the file until where you have to start completion: use std::borrow::Cow;
use std::cmp::Reverse;
use std::sync::Arc;

use aexecutor::SearcherExecutorPool;
use anyhow::{anyhow, Error, Result};
use hashbrown::HashMap;
use serde::{Deserialize, Serialize};
use tantivy::collector::{Count, TopDocs};
use tantivy::fastfield::FastFieldReader;
use tantivy::query::{Query, TermQuery};
use tantivy::schema::{Field, FieldType, IndexRecordOption, Schema, Value};
use tantivy::{
    DateTime,
    DocAddress,
    DocId,
    Executor,
    IndexReader,
    LeasedItem,
    ReloadPolicy,
    Score,
    Searcher,
    SegmentReader,
    Term,
};

use crate::helpers::{AsScore, Validate};
use crate::query::{DocumentId, QueryBuilder, QuerySelector};
use crate::schema::SchemaContext;
use crate::structures::{DocumentHit, IndexContext};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub(crate) struct ReaderContext {
    //
    
    pub(crate) async fn get_document(&self, id: DocumentId) -> Result<DocumentHit> {
        let id_field = self.query_handler.id_field();
        let document = self
            .pool
            .spawn(move |searcher, executor| {
                let qry = TermQuery::new(
                    Term::from_field_u64(id_field, id),
                    IndexRecordOption::Basic,
                );

                let mut results = searcher.search_with_executor(
                    &qry,
                    &TopDocs::with_limit(1),
                    executor,
                )?;
                if results.is_empty() {
                    return Err(Error::msg(format!(
                        "no document exists with id: '{}'",
                        id
                    )));
                }

                let (_, addr) = results.remove(0);
                let doc = searcher.doc(addr)?;
                let schema = searcher.schema();

                Ok(schema.to_named_doc(&doc))
            })
            .await??;

        Ok(DocumentHit::from_tantivy_document(
            self.schema_ctx.as_ref(),
            id,
            document,
            Some(1.0),
        ))
    }