struct Options;

pub struct Generator<'a, 'b> {
    options: Options,
    context: &'a mut Context<'b>
}

struct Context<'a> {
    fds: Vec<FileDescriptor<'a>>
}

struct FileDescriptor<'a>(&'a u32);

impl<'a> Context<'a> {
    pub fn input_files(&self) -> impl Iterator<Item = &FileDescriptor<'a>> {
        self.fds.iter()
    }
}

impl<'a, 'b> Generator<'a, 'b> {
    fn generate_externals_mod(&self) {
        let collected_input: Box<_> = self.context.input_files().collect();
    }
}