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: mod.rs
    path of file: ./repos/cnosdb/query_server/query/src/extension/expr/selector_function
    
    the code of the file until where you have to start completion: mod bottom;
mod topk;

use spi::query::function::FunctionMetadataManager;
use spi::Result;

pu
    
pub fn register_selector_udfs(func_manager: &mut dyn FunctionMetadataManager) -> Result<()> {
    // extend function...
    // eg.
    //   example::register_udf(func_manager)?;
    bottom::register_udf(func_manager)?;
    topk::register_udf(func_manager)?;
    Ok(())
}