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: unused_unit.rs
    path of file: ./repos/rust-clippy/clippy_lints/src
    
    the code of the file until where you have to start completion: use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::{position_before_rarrow, snippet_opt};
use rustc_ast::visit::FnKind;
use rustc_ast::{ast, ClosureBinder};
use rustc_errors::Applicability;
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::declare_lint_pass;
use rustc_span::{BytePos, Span};

declare_clippy_lint! {
    /// ### What it does
    /// Checks for unit (`()`) expressions that can be removed.
    ///
    /// ### Why is this bad?
    /// Such expressions add no
    
    fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, span: Span, _: ast::NodeId) {
        if let ast::FnRetTy::Ty(ref ty) = kind.decl().output
            && let ast::TyKind::Tup(ref vals) = ty.kind
            && vals.is_empty()
            && !ty.span.from_expansion()
            && get_def(span) == get_def(ty.span)
        {
            // implicit types in closure signatures are forbidden when `for<...>` is present
            if let FnKind::Closure(&ClosureBinder::For { .. }, ..) = kind {
                return;
            }

            lint_unneeded_unit_return(cx, ty, span);
        }
    }