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: heap.rs
    path of file: ./repos/whisper/whisper/src
    
    the code of the file until where you have to start completion: use crate::{
    knowledge_base::{Module, Relation},
    maybe_shared::MaybeShared,
    t
    
    pub fn copy_relation_head(&mut self, module: &Module, relation: &Relation) -> Word {
        let top = self.len();
        let start_address = relation.start.get_address();
        // Subtract `relation.start` from all addresses in the source heap, to relocate them
        // to starting the relation at address 0, then add the current top of the heap to get
        // them properly relocated to the top of our heap.
        let offset = WordOffset::new(top as isize - start_address as isize);
        self.words.resize(top + relation.head_len(), Word::BAD);
        // Dereffing `kb` to `Heap` and then to `[Word]` here.
        self.copy_with_offset(top, &module[start_address..relation.neck], offset);
        relation.start.with_address(top)
    }