def get_null_value_counts(df):
    """
    Returns a Series having the counts of (non zero ) null values of each  column

    :param df: dataframe
    :return: A series with index as the column names and values as the null values in those columns
    """
    null_value_stats = df.isnull().sum(axis=0)
    return null_value_stats[null_value_stats != 0]
