---

## Install FastAPI

The first step is to install FastAPI.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then **install FastAPI**:

<div class="termy">

```console
$ pip install "fastapi[standard]"

func (b *bufPool) Get() []byte {
	bufp := b.pool.Get().(*[]byte)
	return (*bufp)[:b.sz]
}

func newBufPool(sz int) httputil.BufferPool {
	return &bufPool{sz: sz, pool: sync.Pool{
		New: func() interface{} {
			buf := make([]byte, sz)
			return &buf
		},
	}}
}

// ServeHTTP forwards HTTP traffic using the configured transport
func (f *Forwarder) ServeHTTP(w http.ResponseWriter, inReq *http.Request) {
	outReq := new(http.Request)

		}
	}
	return
}

func handleAndGetXdsConfigs(clientConfig *xdsstatus.ClientConfig) []*xdsstatus.ClientConfig_GenericXdsConfig {
	configs := make([]*xdsstatus.ClientConfig_GenericXdsConfig, 0)
	if clientConfig.GetGenericXdsConfigs() != nil {
		configs = clientConfig.GetGenericXdsConfigs()
		return configs
	}

This way, its schema will show up in the API docs user interface:

<img src="/img/tutorial/dataclasses/image01.png">

## Dataclasses in Nested Data Structures

You can also combine `dataclasses` with other type annotations to make nested data structures.

In some cases, you might still have to use Pydantic's version of `dataclasses`. For example, if you have errors with the automatically generated API documentation.

		}
		if port == 0 {
			port = 8021 // Default FTP port, since no port was given.
		}
	}

	// If no TLS certs were provided, server is running in TLS for S3 API
	// we automatically make FTP also run under TLS mode.
	if globalIsTLS && tlsPrivateKey == "" && tlsPublicCert == "" {
		tlsPrivateKey = getPrivateKeyFile()
		tlsPublicCert = getPublicCertFile()
	}

## Dispatch

For synchronous calls, you bring your own thread and are responsible for managing how many simultaneous requests you make. Too many simultaneous connections wastes resources; too few harms latency.

      return x.longValue();
    } else if (exponent > MAX_EXPONENT) {
      return x.signum() * POSITIVE_INFINITY;
    }

    /*
     * We need the top SIGNIFICAND_BITS + 1 bits, including the "implicit" one bit. To make rounding
     * easier, we pick out the top SIGNIFICAND_BITS + 2 bits, so we have one to help us round up or
     * down. twiceSignifFloor will contain the top SIGNIFICAND_BITS + 2 bits, and signifFloor the

# likely to change daily.
ARG CACHEBUSTER=0
RUN echo $CACHEBUSTER

# Setup build and environment
COPY devel.usertools /usertools
COPY devel.bashrc /root/.bashrc
COPY ld.so.conf /dt10/etc/

# Make sure clang is on the path
RUN ln -s /usr/lib/llvm-18/bin/clang /usr/bin/clang

# Setup JAX Python environment.
FROM devel as jax
RUN /setup.packages.sh /cuda.packages.txt
COPY jax.requirements.txt /devel.requirements.txt

    // We use this somewhat weird pattern with an enum for each assertion we want to make as a way
    // of dealing with the fact that one of the assertions is @GwtIncompatible but we don't want to
    // have to have duplicate @GwtIncompatible test methods just to make that assertion.
    for (AssertFailsToDecodeStrategy strategy : AssertFailsToDecodeStrategy.values()) {

  Contributor, if any, and such Derivative Works.

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  grants Recipient a non-exclusive, worldwide, royalty-free patent
  license under Licensed Patents to make, use, sell, offer to sell,
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  if any, in Source Code or other form. This patent license shall
  apply to the combination of the Contribution and the Program if, at