/*
 * Copyright (C) 2025 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either

/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *

```

////

Trong cả hai trường hợp có nghĩa là `item` có thể là một `int` hoặc `str`.

#### Khả năng `None`

Bạn có thể khai báo một giá trị có thể có một kiểu dữ liệu, giống như `str`, nhưng nó cũng có thể là `None`.

Trong Python 3.6 hoặc lớn hơn (bao gồm Python 3.10) bạn có thể khai báo nó bằng các import và sử dụng `Optional` từ mô đun `typing`.

```Python hl_lines="1  4"

/*
 * Copyright (C) 2015 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License

- Initially, only **one** of the sites added for replication may have data. After site-replication is successfully configured, this data is replicated to the other (initially empty) sites. Subsequently, objects may be written to any of the sites, and they will be replicated to all other sites.

- **Removing a site** is not allowed from a set of replicated sites once configured.
- All sites must be using the **same** external IDP(s) if any.

        pairs.add(flags1);
        pairs.add(new AvTimestamp(new byte[8]));
        pairs.add(flags2);

        AvPair result = AvPairs.get(pairs, AvPair.MsvAvFlags);
        assertNotNull(result, "Should find the pair");
        assertEquals(flags1, result, "Should return first occurrence");
    }

    /**
     * Test get method with non-existing type
     */
    @Test