[Python] Issue during file handling in python while 'write' operation

There is a test.txt file which has 'Hello, world' in it already. I am running the code shown below

with open('test.txt','r+') as f:
print(f.read(3))
f.write("wow!")
f.flush()


Final content of test.txt: 'Hello, worldwow!'

My understanding says it should have been 'Helwow!world'.

Even if I mention f.flush() or not the final content of file remains same.

I tried implementing this to get more insight:

with open("test.txt", "r+") as f:
print(f.tell())
print(f.read(3))
print(f.tell())
f.flush()
f.write("wow!")
print(f.tell())


and the output was:

0
Hel
3
16


I could not make out as to why the cursor after write goes to 16. My current Python version is 3.10.0, I tried the same in Google Colab but it's the same.

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