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: lib.rs
    path of file: ./repos/ckb/util/occupied-capacity/macros/src
    
    the code of the file until where you have to start completion: //! TODO(doc): @keroro520
extern crate proc_macro;

use quote::quote;
use syn::{parse_macro_input, Error as SynError};

use ckb_occupied_capacity_core::Capacity;

/// TODO(doc): @keroro520
#[proc_macro]
pub fn capacity_bytes(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let input = parse_macro_input!(input as syn::LitInt);
    let expanded = {
        if input.suffix().is_empty() {
            input
                .base10_parse::<usize>()
                .map_err(|_| {
                    SynError::new(
                        input.span(),
                        "the input should be a positive integer literal",
                    )
                })
                .and_then(|value| {
                    Capacity::bytes(value)
                        .map_err(|_| SynError::new(input.span(), "the input capacity is overflow"))
                        .map(|value| {
                            let shannons =
  
    
pub fn capacity_bytes(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let input = parse_macro_input!(input as syn::LitInt);
    let expanded = {
        if input.suffix().is_empty() {
            input
                .base10_parse::<usize>()
                .map_err(|_| {
                    SynError::new(
                        input.span(),
                        "the input should be a positive integer literal",
                    )
                })
                .and_then(|value| {
                    Capacity::bytes(value)
                        .map_err(|_| SynError::new(input.span(), "the input capacity is overflow"))
                        .map(|value| {
                            let shannons =
                                syn::LitInt::new(&value.as_u64().to_string(), input.span());
                            quote!(Capacity::shannons(#shannons))
                        })
                })
        } else {
            Err(SynError::new(
                input.span(),
                "the input should be an integer literal without any suffix",
            ))
        }
        .unwrap_or_else(|err| err.to_compile_error())
    };
    expanded.into()
}