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: mod.rs
    path of file: ./repos/polars/crates/polars-core/src/series
    
    the code of the file until where you have to start completion: //! Type agnostic columnar data structure.
pub use crate::prelude::ChunkCompare;
use crate::prelude::*;

mod any_value;
pub mod arithmetic;
mod comparison;
mod from;
pub mod implementations;
mod into;
pub(crate) mod iterator;
pub mod ops;
mod series_trait;
pub mod unstable;

use std::borrow::Cow;
use std::hash::{Hash, Hasher};
use std::ops::Deref;

use ahash::RandomState;
use arrow::compute::aggregate::estimated_bytes_size;
use arrow::offset::Offsets;
pub use f
    
    pub fn str_value(&self, index: usize) -> PolarsResult<Cow<str>> {
        let out = match self.0.get(index)? {
            AnyValue::String(s) => Cow::Borrowed(s),
            AnyValue::Null => Cow::Borrowed("null"),
            #[cfg(feature = "dtype-categorical")]
            AnyValue::Categorical(idx, rev, arr) | AnyValue::Enum(idx, rev, arr) => {
                if arr.is_null() {
                    Cow::Borrowed(rev.get(idx))
                } else {
                    unsafe { Cow::Borrowed(arr.deref_unchecked().value(idx as usize)) }
                }
            },
            av => Cow::Owned(format!("{av}")),
        };
        Ok(out)
    }