// Singleton contains a pointer to T that must be set once.
// Until the value is set all Get() calls will block.
type Singleton[T any] struct {
	v   *T
	set chan struct{}
}

// NewSingleton creates a new unset singleton.
func NewSingleton[T any]() *Singleton[T] {
	return &Singleton[T]{set: make(chan struct{}), v: nil}
}

// Get will return the singleton value.
func (s *Singleton[T]) Get() *T {
	<-s.set
	return s.v
}

     * Creates a new XmlNode instance with the specified name and value.
     *
     * @param name the name for the new node
     * @param value the value for the new node
     * @return a new XmlNode instance
     * @throws NullPointerException if name is null
     */
    static XmlNode newInstance(String name, String value) {
        return newBuilder().name(name).value(value).build();
    }

    /**

  /**
   * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is
   * present. This will only return a value that was bound to this specific type, not a value that
   * may have been bound to a subtype.
   */
  <T extends @NonNull B> @Nullable T getInstance(TypeToken<T> type);

  /**
   * Maps the specified class to the specified value. Does <i>not</i> associate this value with any

  /**
   * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is
   * present. This will only return a value that was bound to this specific type, not a value that
   * may have been bound to a subtype.
   */
  <T extends @NonNull B> @Nullable T getInstance(TypeToken<T> type);

  /**
   * Maps the specified class to the specified value. Does <i>not</i> associate this value with any

    }
    return max;
  }

  /**
   * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
   *
   * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
   * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
   * value} is greater than {@code max}, {@code max} is returned.
   *

   *
   * @param replacementMap a map of characters to their escaped representations
   * @param safeMin the lowest character value in the safe range
   * @param safeMax the highest character value in the safe range
   */
  protected ArrayBasedCharEscaper(
      Map<Character, String> replacementMap, char safeMin, char safeMax) {

     *
     * @param key the property key to look up
     * @param defaultValue the default value if the property is not found or invalid
     * @return the long value or default value
     */
    protected Long getDefaultLong(final String key, final Long defaultValue) {
        final String value = systemProperties.getProperty(key);
        if (value != null) {
            try {

//       olderThan: 70h # match objects older than this value
//       createdBefore: "2006-01-02T15:04:05.00Z" # match objects created before "date"
//       tags:
//         - key: name
//           value: pick* # match objects with tag 'name', all values starting with 'pick'
//       metadata:
//         - key: content-type
//           value: image/* # match objects with 'content-type', all values starting with 'image/'
//       size:

    }
    return max;
  }

  /**
   * Returns the value nearest to {@code value} which is within the closed range {@code [min..max]}.
   *
   * <p>If {@code value} is within the range {@code [min..max]}, {@code value} is returned
   * unchanged. If {@code value} is less than {@code min}, {@code min} is returned, and if {@code
   * value} is greater than {@code max}, {@code max} is returned.
   *

        String tokenPattern = "name=\"authenticity_token\" +value=\"([^\"]+)\"";
        String content = "<input name=\"authenticity_token\" value=\"abcdefg\">";
        assertEquals("abcdefg", formScheme.getTokenValue(tokenPattern, content));

        tokenPattern = "name=\"authenticity_token\" +value=\"[^\"]+\"";
        content = "<input name=\"authenticity_token\" value=\"abcdefg\">";