code: public String getValue(String name, String defaultValue) {
          return getValue(resolveOption(name), defaultValue);
      }
docs: Retrieve the first argument, if any, of an option.
  
  @param name the name of the option
  @param defaultValue the default value to be returned if the option
  is not specified
  @return the value of the argument if option is set, and has an argument,
  otherwise {@code defaultValue}