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: unique.rs
    path of file: ./repos/polars/crates/polars-ops/src/series/ops
    
    the code of the file until where you have to start completion: use std::hash::Hash;

use polars_core::hashing::_HASHMAP_INIT_SIZE;
use polars_core::prelude::*;
use polars_core::utils::NoNull;
use polars_core::with_match_physical_numeric_polars_type;
use polars_utils::total_ord::{ToTotalOrd, TotalEq, TotalHash};

fn unique_counts_helper<I, J>(items: I) -> IdxCa
where
    I: Iterator<Item = J>,
    J: TotalHash + TotalEq + ToTotalOrd,
    <J as ToTotalOrd>::TotalOrdItem: Hash + Eq,
{
    let mut map = PlIndexMap::with_capacity_and_hasher(_HASHMAP_INIT_SIZE, Default::default());
    for item in items {
        let item = item.to_total_ord();
        map.entry(item)
            .and_modify(|cnt| {
                *cnt += 1;
            })
            .or_insert(1 as IdxSize);
    }
    let out: NoNull<IdxCa> = map.into_values().collect();
    out.into_inner()
}

/// Returns a count of the unique values 
    
pub fn unique_counts(s: &Series) -> PolarsResult<Series> {
    if s.dtype().to_physical().is_numeric() {
        let s_physical = s.to_physical_repr();

        with_match_physical_numeric_polars_type!(s_physical.dtype(), |$T| {
            let ca: &ChunkedArray<$T> = s_physical.as_ref().as_ref().as_ref();
            Ok(unique_counts_helper(ca.iter()).into_series())
        })
    } else {
        match s.dtype() {
            DataType::String => {
                Ok(unique_counts_helper(s.str().unwrap().into_iter()).into_series())
            },
            DataType::Null => {
                let ca = if s.is_empty() {
                    IdxCa::new(s.name(), [] as [IdxSize; 0])
                } else {
                    IdxCa::new(s.name(), [s.len() as IdxSize])
                };
                Ok(ca.into_series())
            },
            dt => {
                polars_bail!(opq = unique_counts, dt)
            },
        }
    }
}