def test_size(STDictonary_root, count=0):
    """Test function for the size counter of the STDict-class, STDictonary_root = root of STDict to test , O(n)"""
    if STDictonary_root is None:
        return count
    else:
        count += 1
        count = test_size(STDictonary_root._left, count)
        count = test_size(STDictonary_root._right, count)

    return count