Question: I have a csv file with a huge dataset containing two columns. I want to compare the data of these two columns such that, if a duplicated pair is present then it gets deleted. For example, if my data file looks something like this:

```
Column A             Column B
DIP-1N                  DIP-1N
DIP-2N                  DIP-3N
DIP-3N                  DIP-2N
DIP-4N                  DIP-5N

```

Then the first entry gets deleted because I don't want two "DIP-1Ns". Also, the order of occurrence of pair is not an issue as far as the entry is unique. For example, here, DIP-2N & DIP-3N and DIP-3N & DIP-3N are paired. But both the entries mean the same thing. So I want to keep one entry and delete the rest.

I have written the following code, but I don't know how to compare simultaneously the entry of both the columns.

```
import csv
import pandas as pd

file = pd.read_csv("/home/staph.csv")
for i in range(len(file['Column A'])):
    for j in range(len(file['Column B'])):
        list1 = []
        list2 = []
        list1.append(file[file['Column A'].str.contains('DIP-'+str(i)+'N')])
        list2.append(file[file['Column B'].str.contains('DIP-'+str(i)+'N')])
        for ele1,ele2 in list1,list2:
            if(list1[ele1]==list2[ele2]):
                print("Duplicate")
            else:
                print("The 1st element is :", ele1)
                print("The 2nd element is :", ele2)

```

Seems like something is wrong, as there is no output. The program just ends without any output or error. Any help would be much appreciated in terms of whether my code is wrong or if I can optimize the process in a better way. Thanks :)

Answer: 
The solution was to change the `POST` variable name to lowercase in the get-data.js file
I had the same error for a different reason, and the syntax in your question and answer has changed again so I'll add my discoveries:

* `+page.server.ts` should no longer `export const POST` but instead `export const actions: Actions = { ... }` which don't need to return anything.
* `+server.ts` still uses `function POST(event: RequestEvent)` and needs to return a `Response` (from the Fetch API).
* Cookies can no longer be set with `setHeaders` but must use `cookies` instead. Otherwise the handler also returns 405.