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: constant.rs
    path of file: ./repos/tower/tower/src/load
    
    the code of the file until where you have to start completion: //! A constant [`Load`] implementation.

#[cfg(feature = "discover")]
use crate::discover::{Change, Discover};
#[cfg(feature = "discover")]
use futures_core::{ready, Stream};
#[cfg(feature = "discover")]
use std::pin::Pin;

use super::Load;
use pin_project_lite::pin_project;
use std::task::{Context, Poll};
use tower_service::Service;

pin_project! {
    #[derive(Debug)]
    /// Wraps a type so that it impleme
    
    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        use self::Change::*;

        let this = self.project();
        let change = match ready!(Pin::new(this.inner).poll_discover(cx)).transpose()? {
            None => return Poll::Ready(None),
            Some(Insert(k, svc)) => Insert(k, Constant::new(svc, *this.load)),
            Some(Remove(k)) => Remove(k),
        };

        Poll::Ready(Some(Ok(change)))
    }