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: hash.rs
    path of file: ./repos/Daft/src/daft-table/src/ops
    
    the code of the file until where you have to start completion: use std::{
    collections::{hash_map::RawEntryMut, HashMap},
    hash::{BuildHasherDefault, Hash, Hasher},
};

use common_error::{DaftError, DaftResult};
use daft_core::{
    array::ops::arrow2::comparison::build_multi_array_is_equal, datatypes::UInt64Array,
};

use daft_core::array::ops::as_arrow::AsArrow;

use crate::Table;

pub struct IndexHash {
    p
    
    pub fn hash_rows(&self) -> DaftResult<UInt64Array> {
        if self.num_columns() == 0 {
            return Err(DaftError::ValueError(
                "Attempting to Hash Table with no columns".to_string(),
            ));
        }
        let mut hash_so_far = self.columns.first().unwrap().hash(None)?;
        for c in self.columns.iter().skip(1) {
            hash_so_far = c.hash(Some(&hash_so_far))?;
        }
        Ok(hash_so_far)
    }