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: integer_range_search.rs
    path of file: ./repos/tantivy/examples
    
    the code of the file until where you have to start completion: // # Searching a range on an indexed int field.
//
// Below is an example of creating an indexed integer field in your schema
// You can use RangeQuery to get a Count of all occurrences in a given range.
use tantivy::collector::Count;
use tantivy::query::RangeQuery;
use tantivy::schema::{Schema, INDEXED};
use tantivy::{doc, Index, IndexWriter, Result};

fn main() -> Result<()> {
    // For the sake of simplicity, this schema will only have 1 field
    let mut schema_builder = Schema::builder();

    // `INDEXED` is a short-hand to indicate that our field should be "searchable".
    let year_field = schema_builder.add_u64_field("year", INDEXED);
    let schema = schema_builder.build();
    let index
    
fn main() -> Result<()> {
    // For the sake of simplicity, this schema will only have 1 field
    let mut schema_builder = Schema::builder();

    // `INDEXED` is a short-hand to indicate that our field should be "searchable".
    let year_field = schema_builder.add_u64_field("year", INDEXED);
    let schema = schema_builder.build();
    let index = Index::create_in_ram(schema);
    let reader = index.reader()?;
    {
        let mut index_writer: IndexWriter = index.writer_with_num_threads(1, 6_000_000)?;
        for year in 1950u64..2019u64 {
            index_writer.add_document(doc!(year_field => year))?;
        }
        index_writer.commit()?;
        // The index will be a range of years
    }
    reader.reload()?;
    let searcher = reader.searcher();
    // The end is excluded i.e. here we are searching up to 1969
    let docs_in_the_sixties = RangeQuery::new_u64("year".to_string(), 1960..1970);
    // Uses a Count collector to sum the total number of docs in the range
    let num_60s_books = searcher.search(&docs_in_the_sixties, &Count)?;
    assert_eq!(num_60s_books, 10);
    Ok(())
}