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/ink/integration-tests/static-buffer
    
    the code of the file until where you have to start completion: #![cfg_attr(not(feature = "std"), no_std, no_main)]

#[ink::contract]
pub mod static_buffer {
    use ink::prelude::{
        string::String,
        vec::Vec,
    };
    
        pub fn buffer(&self) -> Result<(u64, u64), String> {
            let buf1 = Vec::<u8>::with_capacity(3);
            let buf2 = Vec::<u64>::with_capacity(1);
            let ptr1 = buf1.as_ptr() as u64;
            let ptr2 = buf2.as_ptr() as u64;
            let align = core::mem::align_of::<Vec<u64>>() as u64;
            let padding = ptr2
                .checked_sub(ptr1)
                .ok_or(String::from("Error during padding calculation"))?;
            Ok((padding, align))
        }