* Returns an <b>unwrapped</b> argument at the position {@code pos} or {@code null} if the {@code pos} is greater or equal than {@link #getArgsCount()}.
     * This method is useful for handling optional arguments represented as "telescopic" overloads, like the one of the {@code Runtime.exec}:
     * <pre>
     *     Runtime.exec("/usr/bin/echo")
     *     Runtime.exec("/usr/bin/echo", new String[] {"FOO=BAR"})
     * </pre>
     *