# Tutorial - User Guide { #tutorial-user-guide }

This tutorial shows you how to use **FastAPI** with most of its features, step by step.

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference so you can come back and see exactly what you need.

## Run the code { #run-the-code }

import static org.codelibs.opensearch.runner.OpenSearchRunner.newConfigs;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;

import org.codelibs.fess.crawler.client.FesenClient;
import org.codelibs.fess.crawler.entity.OpenSearchUrlQueue;
import org.codelibs.opensearch.runner.OpenSearchRunner;

package cmd

import (
	"bytes"
	"context"
	"encoding/gob"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"maps"
	"math/rand"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	jsoniter "github.com/json-iterator/go"
	"github.com/minio/minio/internal/bucket/lifecycle"
	"github.com/minio/minio/internal/bucket/object/lock"
	"github.com/minio/minio/internal/bucket/versioning"

import java.io.InputStream;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.pdfbox.Loader;
import org.apache.pdfbox.cos.COSInputStream;

import static java.security.AccessController.doPrivileged;
import static java.util.Objects.requireNonNull;
import static java.util.concurrent.TimeUnit.NANOSECONDS;
import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;
import static java.util.logging.Level.SEVERE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.VisibleForTesting;

package cmd

import (
	"bytes"
	"context"
	"encoding/hex"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"path"
	"strconv"
	"strings"
	"sync/atomic"
	"time"

	"github.com/minio/madmin-go/v3"
	"github.com/minio/minio/internal/bpool"
	"github.com/minio/minio/internal/cachevalue"
	"github.com/minio/minio/internal/grid"
	xhttp "github.com/minio/minio/internal/http"

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import org.jspecify.annotations.Nullable;

/**
 * An implementation of {@link GraphConnections} for directed graphs.
 *
 * @author James Sexton
 * @author Jens Nyman

        B = HH(B, C, D, A, X[15], 15);

        context[0] += A;
        context[1] += B;
        context[2] += C;
        context[3] += D;
    }

    // The basic MD4 atomic functions.

    private int FF(final int a, final int b, final int c, final int d, final int x, final int s) {
        final int t = a + (b & c | ~b & d) + x;
        return t << s | t >>> 32 - s;
    }

import java.util.Arrays;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import javax.crypto.SecretKey;

import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

/**
 * Test class for SecureKeyManager

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/** Benchmarks for {@link ExecutionList}. */