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: main.rs
    path of file: ./repos/candle/candle-examples/examples/custom-ops
    
    the code of the file until where you have to start completion: // This example illustrates how to implement custom operations. These operations can provide their
// own forward pass (CPU and GPU versions) as well as their backward pass.
//
// In this exampl
    
    fn cpu_fwd(&self, storage: &CpuStorage, layout: &Layout) -> Result<(CpuStorage, Shape)> {
        let (dim1, dim2) = layout.shape().dims2()?;
        let slice = storage.as_slice::<f32>()?;
        let src = match layout.contiguous_offsets() {
            None => candle::bail!("input has to be contiguous"),
            Some((o1, o2)) => &slice[o1..o2],
        };
        let mut dst = Vec::with_capacity(dim1 * dim2);
        for idx1 in 0..dim1 {
            let src = &src[idx1 * dim2..(idx1 + 1) * dim2];
            let variance = src.iter().map(|x| x * x).sum::<f32>();
            let s_variance = 1f32 / (variance / dim2 as f32 + self.eps).sqrt();
            dst.extend(src.iter().map(|x| x * s_variance))
        }
        let storage = candle::WithDType::to_cpu_storage_owned(dst);
        Ok((storage, layout.shape().clone()))
    }