def null_check(df):
    """
    Goes through a dataframe by column, reports total null values
    found in each column, and returns total null values found in
    DataFrame
    """
    totalnull = 0
    nulls = 0

    for column in df:
        nulls = df[column].isnull().sum()
        if nulls > 0:
            print('{} total nulls in {}'.format(nulls, column))
            totalnull += nulls

    return totalnull