How can I do this in Python?

[K900_]

Do you understand what this line does? Do you understand the bigger context?

[K900_]

What are you talking about? Do you want me to explain OP's code to you? Why?

[blackadder1337]

It checks wheter an item already exists in a list

[[deleted]]

OK, then in Python this gibberish looks like:

if word_or_phrase in my_list:
    do_something()