def observations_average(observations):
    """
    Returns the average of observations values

    :param observations: observations to calculate the average
    :return: average
    """
    if len(observations) == 1:
        average = observations[0].value.value
    elif len(observations) == 0:
        return 0
    else:
        average = 0
        for observation in observations:
            average += float(observation.value.value)
    return float(average)/len(observations)