Looping a function

[wendysling]

Thank you. This is working. But the columns are not appending to the original dataframe, as I can't add dataframe2 = dataframe.assign(month='').

So how can I append the new columns to the original dataframe and create a new copy?

def add_column_missing(dataframe):
    
    from calendar import month_name
    for month in month_name:
        if month not in list(dataframe):
              dataframe.assign(month='')