If you train Python:
-you can use sets to finger arrays

kek, this is 7Kyu Kata

You will be given a number and you will need to return it as a string in Expanded Form

expandedForm(70304); // Should return '70000 + 300 + 4'

Yes, you have to return a string.

Exactly!, i am not getting the question, should we have to return the string like "7000 + 30" like this?, or should we have to add this?

please tell me how you can improve the performance in python for this kata

true, its very unclear and confusing

number + folding zeroes?)

Not a kata issue, read the instructions again or the posts below, the test is ok. You have to do it by word.

all even indexed characters in each word upper cased, and all odd indexed characters in each word lower cased.

The problem with this kata, there is a test value "This is test" and according to the condition it should be equal to "ThIs iS A TeSt", since every even character is uppercase, but the test is not accepted and it says that the value should be equal to "ThIs Is A TeSt', but the letter i in the word is has index 5 and it should not be in uppercase

Just try reverse logic to encoder;)

passes all tests except one:a huge array of Gollum strings, what to do with it?

kek i died. this is not for 6th :/ imo. but thats subjective