Sum up multiple columns into one columns

Question

I concat data from multiple csv files. How do I sum up the total of each row and print out the total in a newly created column?

import pandas as pd

#To join multiple csv files into one dataframe, use pd.concat
df = pd.concat(
    map(pd.read_csv, ['f0_f1.csv', 'f1_f2.csv', 'f2_f3.csv', 'f3_f4.csv', 'f4_f5.csv']), ignore_index=True)

df.groupby('trace_id').nunique()

This is the output I received. How do I create a new column 'Total' and show the sum of each row's (f0 + f1 +f2 + f3 + f4 + f5)