HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Dave");
    assertEquals(1, goodFriends.size());
    assertEquals(2, immut.size());
    assertEquals(2, mut.size());
  }

  public void testSymmetricDifference() {
    Set<String> friends = newHashSet("Tom", "Joe", "Dave");
    Set<String> enemies = newHashSet("Dick", "Harry", "Tom");

   |
   | It works like this: a POM may declare a repository to use in resolving certain artifacts.
   | However, this repository may have problems with heavy traffic at times, so people have mirrored
   | it to several places.
   |
   | That repository definition will have a unique id, so we can create a mirror reference for that
   | repository, to be used as an alternate download site. The mirror site will be the preferred

We have a lifecycle mapping for the packaging of *jar* below. You see that for this packaging we have a *default* lifecycle and a list of phases where each phase is a comma separated list of goals to run and they are in the form groupId:artifactId:version.

<configuration>
  <lifecycles>
    <lifecycle>
      <id>default</id>
      <phases>
        <process-resources>org.apache.maven.plugins:maven-resources-plugin:resources</process-resources>

                    "operationId": "read_items_items__get",
                    "parameters": [
                        {
                            "description": "Query string for the items to search in the database that have a good match",
                            "required": False,
                            "deprecated": True,
                            "schema": IsDict(
                                {

                    "operationId": "read_items_items__get",
                    "parameters": [
                        {
                            "description": "Query string for the items to search in the database that have a good match",
                            "required": False,
                            "deprecated": True,
                            "schema": IsDict(
                                {

And then, that system (in this case **FastAPI**) will take care of doing whatever is needed to provide your code with those needed dependencies ("inject" the dependencies).

This is very useful when you need to:

* Have shared logic (the same code logic again and again).
* Share database connections.
* Enforce security, authentication, role requirements, etc.
* And many other things...

All these, while minimizing code repetition.

$ export MY_NAME="Wade Wilson"

// Dann könnten Sie diese mit anderen Programmen verwenden, etwa
$ echo "Hello $MY_NAME"

Hello Wade Wilson
```

</div>

////

//// tab | Windows PowerShell

<div class="termy">

```console
// Erstelle eine Umgebungsvariable MY_NAME
$ $Env:MY_NAME = "Wade Wilson"

// Verwende sie mit anderen Programmen, etwa

   * we're guaranteed to have properly initialized the subclass.
   */
  final void init() {
    /*
     * requireNonNull is safe because this is called from the constructor after `futures` is set but
     * before releaseResources could be called (because we have not yet set up any of the listeners

                    },
                    "summary": "Create an item",
                    "description": "Create an item with all the information:\n\n- **name**: each item must have a name\n- **description**: a long description\n- **price**: required\n- **tax**: if the item doesn't have tax, you can omit this\n- **tags**: a set of unique tag strings for this item",
                    "operationId": "create_item_items__post",
                    "requestBody": {

type Tag struct {
	XMLName xml.Name `xml:"Tag"`
	Key     string   `xml:"Key,omitempty"`
	Value   string   `xml:"Value,omitempty"`
}

var (
	errInvalidTagKey   = Errorf("The TagKey you have provided is invalid")
	errInvalidTagValue = Errorf("The TagValue you have provided is invalid")

	errDuplicatedXMLTag = Errorf("duplicated XML Tag")
	errUnknownXMLTag    = Errorf("unknown XML Tag")
)

// UnmarshalXML - decodes XML data.