В прежних версиях NodeJS/браузерного JavaScript вы бы использовали «callbacks» (обратные вызовы), что приводит к «callback hell» (ад обратных вызовов).

## Сопрограммы { #coroutines }

                        it.set(interpolator.interpolate(it.next(), callback));
                    }
                }
                commandLineBuilder.addOption(option);
            }
            for (String arg : commandLine.getArgList()) {
                commandLineBuilder.addArg(interpolator.interpolate(arg, callback));
            }
            return copy(source, cliManager, commandLineBuilder.get());

    /**
     * Validates the password and confirmation fields in the form for user creation and update.
     *
     * @param form the form containing password and confirmation fields
     * @param validationErrorLambda callback to report validation errors
     */
    protected void verifyPassword(final CreateForm form, final VaErrorHook validationErrorLambda) {
        if (form.crudMode == CrudMode.CREATE && StringUtil.isBlank(form.password)) {

                return BASE64URL_DECODER.decode(base64String.trim());
            }
            throw e;
        }
    }

    /**
     * Processes the callback from OpenID Connect provider.
     *
     * @param request the HTTP servlet request
     * @param code the authorization code
     * @return the login credential
     */

NodeJS / Browser JavaScript'in önceki sürümlerinde, "callback" kullanırdınız. Bu da "callbacks cehennemine" yol açar.

## Coroutine'ler

 * **Synchronous:** your thread blocks until the response is readable.
 * **Asynchronous:** you enqueue the request on any thread, and get [called back](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-callback/) on another thread when the response is readable.

        // Create GroovyShell with custom class loader for proper resource management
        GroovyClassLoader classLoader = null;
        try {
            // Get parent class loader with fallback to ensure robustness across threading contexts
            ClassLoader parentClassLoader = Thread.currentThread().getContextClassLoader();
            if (parentClassLoader == null) {

        public RequestOptionCall<DeleteRequestBuilder> deleteOption() {
            return deleteOption;
        }
    }

    @FunctionalInterface
    public interface RequestOptionCall<OP> {
        void callback(OP op);
    }

            // we called sizeIfKnown and when we started reading the file (or I guess if
            // maxCharsPerByte is wrong)
            // Fallback to an incremental approach
            StringBuilder builder = new StringBuilder(bufIndex + 32);
            builder.append(buffer, 0, bufIndex);
            buffer = null; // release for gc

      } else {
        sslSocket.enabledProtocols
      }

    // In accordance with https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00 the SCSV
    // cipher is added to signal that a protocol fallback has taken place.
    val supportedCipherSuites = sslSocket.supportedCipherSuites
    val indexOfFallbackScsv =
      supportedCipherSuites.indexOf(
        "TLS_FALLBACK_SCSV",
        CipherSuite.ORDER_BY_NAME,