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: difficulty.rs
    path of file: ./repos/ckb/util/types/src/utilities
    
    the code of the file until where you have to start completion: use numext_fixed_uint::prelude::UintConvert;
use numext_fixed_uint::{u512, U256, U512};

/// The minimal difficulty that can be represented in the compact format.
pub const DIFF_TWO: u32 = 0x2080_0000;

const ONE: U256 = U256::one();
// ONE << 
    
pub fn target_to_compact(target: U256) -> u32 {
    let bits = 256 - target.leading_zeros();
    let exponent = u64::from((bits + 7) / 8);
    let mut compact = if exponent <= 3 {
        get_low64(&target) << (8 * (3 - exponent))
    } else {
        get_low64(&(target >> (8 * (exponent - 3))))
    };

    compact |= exponent << 24;
    compact as u32
}