You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "who sang the theme song to fireball xl5?" whose answer is Don Spencer.
Each document should contain about 30 words, and these documents should contain useful information.

Query: theme song Fireball XL5 singer
Useful Output:

Doc 1: Wowit was 60 years ago that I recorded the theme song for the t.v. show 'Fireball XL5' wonderful memories of where it all began. ABC Music
Doc 2:  theme music to Gerry and Sylvia Anderson's first SF TV puppet series, Fireball XL5. Sung by Australian singer Don Spencer, in a shorter
Doc 3: Fireball XL5's Steve Zodiac croons the show's theme song! Who knows the words well enough to sing along?
Doc 4: Felix Jones's somewhat official theme song "Fireball XL5". 72K views · 4 years ago #magicperformance #felixjonesmagic #felixjones more
Doc 5: Man, what a blast from the past. Love this theme song. It's one of those that just makes one feel good. I remember watching this as a kid.