The following produces a file containingb'hello\n ', i.e.hello followed by a newline and a space:

withopen("asd.txt","w")asfile:file.write("hello\n")withopen("asd.txt","r+")asfile:file.read(4)file.write(" ")

But if I addfile.seek(file.tell()), then it instead producesb'hell \n' as I would expect:

withopen("asd.txt","w")asfile:file.write("hello\n")withopen("asd.txt","r+")asfile:file.read(4)file.seek(file.tell())file.write(" ")

Is this correct behaviour? I can't find any mention of it in the docs. (I can't usefile.seek(4) because that "produces undefined behaviour" according to docs.)