UnicodeEscaper e = new PercentEscaper("%", false);
    assertEquals("foo%7Cbar", e.escape("foo|bar"));
    assertEquals("foo%7Cbar", e.escape("foo%7Cbar")); // idempotent
  }

  /** Test that giving a null 'safeChars' string causes a {@link NullPointerException}. */
  public void testBadArguments_null() {
    assertThrows(NullPointerException.class, () -> new PercentEscaper(null, false));
  }

  /**

## Pydantic `Settings` { #pydantic-settings }

Fortunately, Pydantic provides a great utility to handle these settings coming from environment variables with <a href="https://docs.pydantic.dev/latest/concepts/pydantic_settings/" class="external-link" target="_blank">Pydantic: Settings management</a>.

Examples of behavior that contributes to a positive environment for our
community includes:

* Demonstrating empathy and kindness toward other people
* Being respectful of differing opinions, viewpoints, and experiences
* Giving and gracefully accepting constructive feedback
* Accepting responsibility and apologizing to those affected by our mistakes,
  and learning from the experience
* Focusing on what is best not just for us as individuals, but for the

        ensurePositive(xSumOfSquaresOfDeltas * ySumOfSquaresOfDeltas);
    return ensureInUnitRange(sumOfProductsOfDeltas / Math.sqrt(productOfSumsOfSquaresOfDeltas));
  }

  /**
   * Returns a linear transformation giving the best fit to the data according to <a
   * href="http://mathworld.wolfram.com/LeastSquaresFitting.html">Ordinary Least Squares linear

   capacity and competence.

 * **Be considerate**: People use our work, and we depend on the work of others. Consider users and
   colleagues before taking action. For example, changes to code, infrastructure, policy, and
   documentation may negatively impact others.

 * **Be respectful**: We expect people to work together to resolve conflict, assume good intentions,

		if !globalIAMSys.Initialized() {
			// Check if server has initialized, then only proceed
			// to check for IAM users otherwise its okay for clients
			// to retry with 503 errors when server is coming up.
			return auth.Credentials{}, false, ErrIAMNotInitialized
		}

		// Check if the access key is part of users credentials.
		u, ok, err := globalIAMSys.CheckKey(r.Context(), accessKey)
		if err != nil {

        ensurePositive(xSumOfSquaresOfDeltas * ySumOfSquaresOfDeltas);
    return ensureInUnitRange(sumOfProductsOfDeltas / Math.sqrt(productOfSumsOfSquaresOfDeltas));
  }

  /**
   * Returns a linear transformation giving the best fit to the data according to <a
   * href="http://mathworld.wolfram.com/LeastSquaresFitting.html">Ordinary Least Squares linear

# Classes as Dependencies { #classes-as-dependencies }

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example { #a-dict-from-the-previous-example }

In the previous example, we were returning a `dict` from our dependency ("dependable"):

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

          state = STATE_READ_RESPONSE_HEADERS
          responseBuilder
        }
        statusLine.code in (102 until 200) -> {
          // Processing and Early Hints will mean a second headers are coming.
          // Treat others the same for now
          state = STATE_READ_RESPONSE_HEADERS
          responseBuilder
        }
        else -> {
          state = STATE_OPEN_RESPONSE_BODY

   *     the {@link ExecutionException} thrown by {@code input.get()} or, if {@code get()} throws a
   *     different kind of exception, that exception itself. To avoid hiding bugs and other
   *     unrecoverable errors, callers should prefer more specific types, avoiding {@code
   *     Throwable.class} in particular.