# Body - Nested Models

With **FastAPI**, you can define, validate, document, and use arbitrarily deeply nested models (thanks to Pydantic).

## List fields

You can define an attribute to be a subtype. For example, a Python `list`:

//// tab | Python 3.10+

```Python hl_lines="12"
{!> ../../docs_src/body_nested_models/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="14"

    But, when the tide rises and sharks are around,
    His voice has a timid and tremulous sound.]

  `That's different from what I used to say when I was a child,'
said the Gryphon.

  `Well, I never heard it before,' said the Mock Turtle; `but it
sounds uncommon nonsense.'

  Alice said nothing; she had sat down with her face in her
hands, wondering if anything would EVER happen in a natural way

before a garbage collection delays that cycle. Less frequent cycles means
the CPU cost of the garbage collector is incurred less frequently.

This functionality in this package is mostly captured in the Arena type.
Arenas allocate large chunks of memory for Go values, so they're likely to
be inefficient for allocating only small amounts of small Go values. They're
best used in bulk, on the order of MiB of memory allocated on each use.

   * @throws NullPointerException if {@code string} is null
   */
  @Override
  public String escape(String string) {
    checkNotNull(string); // GWT specific check (do not optimize)
    // Inlineable fast-path loop which hands off to escapeSlow() only if needed
    int length = string.length();
    for (int index = 0; index < length; index++) {
      if (escape(string.charAt(index)) != null) {
        return escapeSlow(string, index);
      }

		t.Parallel()
		if !generatesZip64(t, gen(uint32max)) {
			t.Error("expected zip64")
		}
	})
}

func testZip64(t testing.TB, size int64) *rleBuffer {
	const chunkSize = 1024
	chunks := int(size / chunkSize)
	// write size bytes plus "END\n" to a zip file
	buf := new(rleBuffer)
	w := NewWriter(buf)
	f, err := w.CreateHeader(&FileHeader{
		Name:   "huge.txt",
		Method: Store,
	})

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![ReDoc](https://fastapi.tiangolo.com/img/index/index-06-redoc-02.png)

### Just Modern Python

It's all based on standard **Python type** declarations (thanks to Pydantic). No new syntax to learn. Just standard modern Python.

        val releaseNotesLines: List<String> = releaseNotes.asFile.get().readLines()
        val contributorSectionBeginIndex = releaseNotesLines.indexOfFirst { it.startsWith("We would like to thank the following community members for their contributions to this release of Gradle:") } + 1

        if (contributorSectionBeginIndex == 0) {
            error("Can't find the contributors section in the release notes $releaseNotes.")

How to contribute
=================

Thank you so much for wanting to contribute to Guava! Here are a few important
things you should know about contributing:

1.  API changes require discussion, use cases, etc. Code comes later.
2.  Pull requests are great for small fixes for bugs, documentation, etc.
3.  Pull requests are not merged directly into the master branch.
4.  Code contributions require signing a Google CLA.

API changes
-----------

	"context"
	"hash"
	"io"
	"sync"

	xhttp "github.com/minio/minio/internal/http"
	"github.com/minio/minio/internal/ioutil"
	"github.com/minio/minio/internal/ringbuffer"
)

// Calculates bitrot in chunks and writes the hash into the stream.
type streamingBitrotWriter struct {
	iow          io.WriteCloser
	closeWithErr func(err error)
	h            hash.Hash
	shardSize    int64
	canClose     *sync.WaitGroup