def unique():
    """
    Generates a new pseudo unique identifier generated in the
    most efficient way by incrementing a global counter.

    This operation should be used for observer based contexts
    and not outside it, in order to avoid possible problems.

    :rtype: int
    :return: The pseudo unique integer identifier generated by
    incrementing the global counter value.
    """
    global COUNTER
    COUNTER += 1
    return COUNTER
