# Configurações e Variáveis de Ambiente

Em muitos casos a sua aplicação pode precisar de configurações externas, como chaves secretas, credenciais de banco de dados, credenciais para serviços de email, etc.

A maioria dessas configurações é variável (podem mudar), como URLs de bancos de dados. E muitas delas podem conter dados sensíveis, como tokens secretos.

Por isso é comum prover essas configurações como variáveis de ambiente que são utilizidas pela aplicação.

    ```

 *  New: Make the content-type header optional for request bodies.
 *  New: `Response.isSuccessful()` is a convenient API to check response codes.
 *  New: The response body can now be read outside of the callback. Response
    bodies must always be closed, otherwise they will leak connections!
 *  New: APIs to create multipart request bodies (`MultipartBuilder`) and form
    encoding bodies (`FormEncodingBuilder`).

 *
 * <p>This class serializes execution of <i>submitted</i> tasks but not any <i>listeners</i> of
 * those tasks.
 *
 * <p>Submitted tasks have a happens-before order as defined in the Java Language Specification.
 * Tasks execute with the same happens-before order that the function calls to {@link #submit} and
 * {@link #submitAsync} that submitted those tasks had.
 *
 * <p>This class has limited support for cancellation and other "early completions":

   */
  static void checkNo2BitCharacteristics(HashFunction function) {
    Random rand = new Random(0);
    int keyBits = 32;

    // get every one of (keyBits choose 2) deltas:
    for (int i = 0; i < keyBits; i++) {
      for (int j = 0; j < keyBits; j++) {
        if (j <= i) continue;
        int count = 0;
        int maxCount = 20; // the probability of error here is minuscule

            if (
                // ie modal dialog fix
                e.type == "focusin" ||
                target.closest(this.element).length ||
                target.closest(this.container).length ||
                target.closest('.calendar-table').length
                ) return;
            this.hide();
            this.element.trigger('outsideClick.daterangepicker', this);
        },

As Python advances, **newer versions** come with improved support for these type annotations and in many cases you won't even need to import and use the `typing` module to declare the type annotations.

If you can choose a more recent version of Python for your project, you will be able to take advantage of that extra simplicity.

	dcomp := r.decompressors[method]
	if dcomp == nil {
		dcomp = decompressor(method)
	}
	return dcomp
}

// Close closes the Zip file, rendering it unusable for I/O.
func (rc *ReadCloser) Close() error {
	return rc.f.Close()
}

// DataOffset returns the offset of the file's possibly-compressed
// data, relative to the beginning of the zip file.
//

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   *
   * <p>For a new instance, where the arrays above have not yet been allocated, the value of {@code

   * the discussion in the {@link #addListener} documentation. All its warnings about heavyweight
   * listeners are also applicable to heavyweight functions passed to this method.
   *
   * <p>This method is similar to {@link java.util.concurrent.CompletableFuture#exceptionally}. It
   * can also serve some of the use cases of {@link java.util.concurrent.CompletableFuture#handle}

var errMalformedEncoding = errors.New("malformed chunked encoding")

// chunk is considered too big if its bigger than > 16MiB.
var errChunkTooBig = errors.New("chunk too big: choose chunk size <= 16MiB")

// newSignV4ChunkedReader returns a new s3ChunkedReader that translates the data read from r
// out of HTTP "chunked" format before returning it.