How to add new rows to existing csv file

[Sri]

Hi,

I have test.csv file as show below

Category Value
Initial Target 30
new target 49
recovery time [hrs] 2

Now I want to add new rows stored in string format (remove: ****new data****)

webdata:

****new data****
Reset time [min],78
Warning value,23
Error range, -4


I use the following code but it did not update.

webdata='****new data****
Reset time [min],78
Warning value,23
Error range, -4 '
import csv
with open(r'test.csv', 'a') as f:
    writer = csv.writer(f)
    writer.writerow(webdata)