def get_unique_last_str(df):
    '''
    AIM    -> get unique last str for a column
     
    INPUT  -> df
    
    OUTPUT -> updated df based on the unique last strings in a column 
    ------
    '''
    df = df[df.index.isin(df['col_1'].drop_duplicates(keep='last').index)].reset_index(drop=True)
    return df