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: lib.rs
    path of file: ./repos/wasmtime/crates/misc/component-fuzz-util/src
    
    the code of the file until where you have to start completion: //! This module generates test cases for the Wasmtime component model function APIs,
//! e.g. `wasmtime::component::func::Func` and `TypedFunc`.
//!
//! Each case includes a list of arbitrary interface types to use as parameters, plus another one to use as a
//! result, and a component which exports a function and imports a function.  The exported function forwards its
//! parameters to the imported one and forwards the result back to the caller.  This serves to excercise Wasmtime's
//! lifting and lowering code and verify the values remain intact during both processes.

use arbitrary::{Arbitrary, Unstructured};
use proc_macro2::{Ident, TokenStream};
use quote::{format_ident, quote, ToTokens};
use std::borrow::Cow;
use std::fmt::{self, Debug, Write};
use std::iter;
use std::ops:
    
    pub fn declarations(&self) -> Declarations {
        let mut builder = TypesBuilder::default();

        let mut params = String::new();
        for (i, ty) in self.params.iter().enumerate() {
            params.push_str(&format!(" (param \"p{i}\" "));
            builder.write_ref(ty, &mut params);
            params.push_str(")");
        }

        let mut results = String::new();
        for (i, ty) in self.results.iter().enumerate() {
            results.push_str(&format!(" (result \"r{i}\" "));
            builder.write_ref(ty, &mut results);
            results.push_str(")");
        }

        let import_and_export = make_import_and_export(&self.params, &self.results);

        let mut type_decls = Vec::new();
        let mut type_instantiation_args = String::new();
        while let Some((idx, ty)) = builder.worklist.pop() {
            type_decls.push(builder.write_decl(idx, ty));
            writeln!(type_instantiation_args, "(with \"t{idx}\" (type $t{idx}))").unwrap();
        }

        // Note that types are printed here in reverse order since they were
        // pushed onto `type_decls` as they were referenced meaning the last one
        // is the "base" one.
        let mut types = String::new();
        for decl in type_decls.into_iter().rev() {
            types.push_str(&decl);
            types.push_str("\n");
        }

        Declarations {
            types: types.into(),
            type_instantiation_args: type_instantiation_args.into(),
            params: params.into(),
            results: results.into(),
            import_and_export: import_and_export.into(),
            encoding1: self.encoding1,
            encoding2: self.encoding2,
        }
    }