def average_above_zero(table):
    """
    make average from a table of non-null positiv value
    Arg:
        table : a list of numeric values
    return:
        he computed average
    raise :
        check if there is no positive value in table
    """
    if not(isinstance(table, list)):
        raise ValueError('expeced a list as input')
    
    average = -1
    sum=0.0
    positifValueNumber=0
    for val in table:
        if val>=0:
            sum=sum+val
            positifValueNumber=positifValueNumber+1
    if positifValueNumber <= 0:
        raise ValueError('any positiv numbre in tab in function average_above_zero')
    
    
    average = sum/positifValueNumber
    return average