// overuse of Clone can make programs use more memory.
// Clone should typically be used only rarely, and only when
// profiling indicates that it is needed.
// For strings of length zero the string "" will be returned
// and no allocation is made.
func Clone(s string) string {
	return stringslite.Clone(s)

// best approach was for Go to raise the limit unconditionally for itself,
// and then leave old software to set the limit back as needed.
// Code that really wants Go to leave the limit alone can set the hard limit,
// which Go of course has no choice but to respect.
func init() {
	var lim Rlimit
	if err := Getrlimit(RLIMIT_NOFILE, &lim); err == nil && lim.Cur != lim.Max {
		origRlimitNofile.Store(&lim)
		nlim := lim
		nlim.Cur = nlim.Max

# Body - Multiple Parameters

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

=== "Python 3.10+"

			Help:           "Number of objects read from storage in the course of serving a LIST request",
			StabilityLevel: compbasemetrics.ALPHA,
		},
		[]string{"resource"},
	)
	listStorageNumSelectorEvals = compbasemetrics.NewCounterVec(
		&compbasemetrics.CounterOpts{
			Name:           "apiserver_storage_list_evaluated_objects_total",
			Help:           "Number of objects tested in the course of serving a LIST request from storage",

// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Support for pidfd was added during the course of a few Linux releases:
//  v5.1: pidfd_send_signal syscall;
//  v5.2: CLONE_PIDFD flag for clone syscall;
//  v5.3: pidfd_open syscall, clone3 syscall;
//  v5.4: P_PIDFD idtype support for waitid syscall;
//  v5.6: pidfd_getfd syscall.

package os

So, even with the code above that doesn't use Pydantic explicitly, FastAPI is using Pydantic to convert those standard dataclasses to Pydantic's own flavor of dataclasses.

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

    A `Response` returned directly by your *path operation function* won't be documented in OpenAPI (for example, the `Content-Type` won't be documented) and won't be visible in the automatic interactive docs.

!!! info
    Of course, the actual `Content-Type` header, status code, etc, will come from the `Response` object you returned.

### Document in OpenAPI and override `Response`

Of course, there are some cases where there's no problem in running the previous steps multiple times, in that case, it's a lot easier to handle.

!!! tip

		&compbasemetrics.CounterOpts{
			Namespace:      namespace,
			Name:           "cache_list_fetched_objects_total",
			Help:           "Number of objects read from watch cache in the course of serving a LIST request",
			StabilityLevel: compbasemetrics.ALPHA,
		},
		[]string{"resource_prefix", "index"},
	)
	listCacheNumReturned = compbasemetrics.NewCounterVec(
		&compbasemetrics.CounterOpts{

Or you might have any other way to communicate with the WebSocket endpoint.

---

But for this example, we'll use a very simple HTML document with some JavaScript, all inside a long string.

This, of course, is not optimal and you wouldn't use it for production.

In production you would have one of the options above.

But it's the simplest way to focus on the server-side of WebSockets and have a working example: