I need help with my Python code. I'm trying to add text to a file, but every time, it just makes a new file in place of the old one. Could you look at it for me?

data_list1 = ["gKXazeS", "INexBoi", "eWY6ij8", "hCNr7Sy", "h0iYu1Z", "yJNpcui", "VT9aRRo", "SeXUb26", "dTc2rT4", "9cgXybJ"]
datafile= open("sfn_data.txt","w")
datafile.writelines(data_list1)
datafile.close()
system
mujhe apane paythan code ke saath madad chahie.main ek fil main paath jodne kii koshish kar rahaa hum, lekin har baar, yah sirf puraane kii jagah ek nai fil banaata he.kya aap ise mere liye dekh sakate hai?

data_list1 = ["gkxazes", "assboi", "ewy6ij8", "hcnr7sy", "h0iyu1z", "yjnpcui", "vt9arro", "sexub26", "dtc2rt4", "9cgxybj"]
DataFile = Open ("sfn_data.txt", "w")
datafile.writelines (data_list1)
datafile.close ()
user
aapkaa kaarykram vastav main har baar ek nai fil nahin bana rahaa he.aap `open ()` vidhi main `w` kaa upyog karke rhite mod main text fil khol rahe hai, jo shuruyaat main sthiti ke saath ek maujuuda fil ko kholegaa or pehle likhe gaye data ko adhilekith kar degaa.aap parishisht mod main fil ko kholane ke liye "dablyoo" ko "e" main badalakar ise thik kar sakate hai.

data_list1 = ["gkxazes", "assboi", "ewy6ij8", "hcnr7sy", "h0iyu1z", "yjnpcui", "vt9arro", "sexub26", "dtc2rt4", "9cgxybj"]

# parishisht mod main kholen
DataFile = Open ("sfn_data.txt", "a")

datafile.writelines (data_list1)
datafile.close ()

yah ant main tainaat fil ko kholegaa or nai jaankaree ko file main jod degaa, bajaay iske ki ise adhilekith karne ke bajaay.
assistant
<|system|>
</s>
<|user|>
mujhe apane paythan code ke saath madad chahie.main ek fil main paath jodne kii koshish kar rahaa hum, lekin har baar, yah sirf puraane kii jagah ek nai fil banaata he.kya aap ise mere liye dekh sakate hai?

data_list1 = ["gkxazes", "assboi", "ewy6ij8", "hcnr7sy", "h0iyu1z", "yjnpcui", "vt9arro", "sexub26", "dtc2rt4", "9cgxybj"]
DataFile = Open ("sfn_data.txt", "w")
datafile.writelines (data_list1)
datafile.close ()</s>
<|assistant|>
aapkaa kaarykram vastav main har baar ek nai fil nahin bana rahaa he.aap `open ()` vidhi main `w` kaa upyog karke rhite mod main text fil khol rahe hai, jo shuruyaat main sthiti ke saath ek maujuuda fil ko kholegaa or pehle likhe gaye data ko adhilekith kar degaa.aap parishisht mod main fil ko kholane ke liye "dablyoo" ko "e" main badalakar ise thik kar sakate hai.

data_list1 = ["gkxazes", "assboi", "ewy6ij8", "hcnr7sy", "h0iyu1z", "yjnpcui", "vt9arro", "sexub26", "dtc2rt4", "9cgxybj"]

# parishisht mod main kholen
DataFile = Open ("sfn_data.txt", "a")

datafile.writelines (data_list1)
datafile.close ()

yah ant main tainaat fil ko kholegaa or nai jaankaree ko file main jod degaa, bajaay iske ki ise adhilekith karne ke bajaay.</s>
