Function slices_for_write 

pub fn slices_for_write(
    manifest: &Manifest,
    path: &str,
    content: &str,
    contract_sources: &[(&str, &str)],
) -> Vec<ContractSlice>

Symbol-level slices for a write of content at path. contract_sources supplies each declared contract’s authoring source text (the mapper is pure — callers own file access).