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: eager.rs
    path of file: ./repos/polars/py-polars/src/functions
    
    the code of the file until where you have to start completion: use polars::functions;
use polars_core::prelude::*;
use polars_core::with_match_physical_integer_polars_type;
use polars_ops::series::new_int_range;
use pyo3::prelude::*;


    
pub fn concat_series(series: &PyAny) -> PyResult<PySeries> {
    let mut iter = series.iter()?;
    let first = iter.next().unwrap()?;

    let mut s = get_series(first)?;

    for res in iter {
        let item = res?;
        let item = get_series(item)?;
        s.append(&item).map_err(PyPolarsErr::from)?;
    }
    Ok(s.into())
}