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: util.rs
    path of file: ./repos/trezor-firmware/core/embed/rust/src/ui/layout
    
    the code of the file until where you have to start completion: use crate::{
    error::Error,
    micropython::{
        buffer::{hexlify_b
    
    fn at(&self, index: usize, offset: usize) -> Paragraph<Self::StrType> {
        let block = move || {
            let entry = self.items.get(index / 2)?;
            let [key, value, value_is_mono]: [Obj; 3] = iter_into_array(entry)?;
            let value_is_mono: bool = bool::try_from(value_is_mono)?;
            let obj: Obj;
            let style: &TextStyle;

            if index % 2 == 0 {
                if !key.is_str() && key != Obj::const_none() {
                    return Err(Error::TypeError);
                }
                style = self.key_font;
                obj = key;
            } else {
                if value_is_mono {
                    style = self.value_mono_font;
                } else {
                    if value.is_bytes() {
                        return Err(Error::TypeError);
                    }
                    style = self.value_font;
                }
                obj = value;
            };

            if obj == Obj::const_none() {
                return Ok(Paragraph::new(style, StrBuffer::empty()));
            }

            let para = if obj.is_str() {
                let content: StrBuffer = obj.try_into()?;
                Paragraph::new(style, content.skip_prefix(offset))
            } else if obj.is_bytes() {
                let content = hexlify_bytes(obj, offset, MAX_HEX_CHARS_ON_SCREEN)?;
                Paragraph::new(style, content)
            } else {
                return Err(Error::TypeError);
            };

            if obj == key && value != Obj::const_none() {
                Ok(para.no_break())
            } else {
                Ok(para)
            }
        };
        match block() {
            Ok(para) => para,
            Err(_) => Paragraph::new(self.value_font, StrBuffer::from("ERROR")),
        }
    }