/// tip

You only need to do this **once per project**, not every time you work.

///

//// tab | `venv`

To create a virtual environment, you can use the `venv` module that comes with Python.

<div class="termy">

```console
$ python -m venv .venv
```

Reading a file from disk is normally a costly (slow) operation, so you probably want to do it only once and then reuse the same settings object, instead of reading it for each request.

But every time we do:

```Python
Settings()
```

a new `Settings` object would be created, and at creation it would read the `.env` file again.

If the dependency function was just like:

```Python

    b *= K3;
    return b;
  }

  /**
   * Computes intermediate hash of 32 bytes of byte array from the given offset. Results are
   * returned in the output array - this is 12% faster than allocating new arrays every time.
   */
  private static void weakHashLength32WithSeeds(
      byte[] bytes, int offset, long seedA, long seedB, long[] output) {
    long part1 = load64(bytes, offset);
    long part2 = load64(bytes, offset + 8);

   * array nor its contents can be null, but it is not useful to force the use of {@code
   * requireNonNull} or the like just to assert that.
   *
   * <p>{@code EqualsTester} will always check that every object it is given returns false from
   * {@code equals(null)}, so it is neither useful nor allowed to include a null value in any
   * equality group.
   */
  @CanIgnoreReturnValue

  private val postponedRoutes = mutableListOf<Route>()

  init {
    resetNextProxy(address.url, address.proxy)
  }

  /**
   * Returns true if there's another set of routes to attempt. Every address has at least one route.
   */
  operator fun hasNext(): Boolean = hasNextProxy() || postponedRoutes.isNotEmpty()

  @Throws(IOException::class)
  operator fun next(): Selection {

   * array nor its contents can be null, but it is not useful to force the use of {@code
   * requireNonNull} or the like just to assert that.
   *
   * <p>{@code EqualsTester} will always check that every object it is given returns false from
   * {@code equals(null)}, so it is neither useful nor allowed to include a null value in any
   * equality group.
   */
  @CanIgnoreReturnValue

/**
 * A support class for {@code ListenableFuture} implementations to manage their listeners. An
 * instance contains a list of listeners, each with an associated {@code Executor}, and guarantees
 * that every {@code Runnable} that is {@linkplain #add added} will be executed after {@link
 * #execute()} is called. Any {@code Runnable} added after the call to {@code execute} is still

   *   <li>{@linkplain LoadingCache#getAll bulk loading requests}, including {@linkplain
   *       CacheLoader#loadAll bulk loading implementations}
   * </ul>
   *
   * <p><b>Warning:</b> For any given key, every {@code loader} used with it should compute the same
   * value. Otherwise, a call that passes one {@code loader} may return the result of another call

   * callback has returned. Synchronous calls become idle once [execute()][Call.execute] returns.
   * This means that if you are doing synchronous calls the network layer will not truly be idle
   * until every returned [Response] has been closed.
   */
  @get:Synchronized
  @set:Synchronized
  var idleCallback: Runnable? = null

  private var executorServiceOrNull: ExecutorService? = null

 * of bugs and confusion.
 *
 * <h3>About <i>all</i> {@code Immutable-} collections</h3>
 *
 * <p>The remainder of this documentation applies to every public {@code Immutable-} type in this
 * package, whether it is a subtype of {@code ImmutableCollection} or not.
 *
 * <h4>Guarantees</h4>
 *
 * <p>Each makes the following guarantees:
 *
 * <ul>