code: public OptionSet addOption(String key, Options.Separator separator, Options.Multiplicity multiplicity) {
      return addOption(key, false, separator, true, multiplicity);
    }
docs: Add a value option with the given key, separator, and multiplicity, no details, and the default prefix
  <p>
  @param key          The key for the option
  @param separator    The separator for the option
  @param multiplicity The multiplicity for the option
  <p>
  @return The set instance itself (to support invocation chaining for <code>addOption()</code> methods)
  <p>
  @throws IllegalArgumentException If the <code>key</code> is <code>null</code> or a key with this name has already been defined
  or if <code>separator</code> or <code>multiplicity</code> are <code>null</code>