Hey up a ree ...

I'm translating a documentary.
It says sth. about American women soldiers of WWII.
Then a woman interviewed recalled the days when they were drilling and marching. She cried,
"Hey up a ree bup a ree bay a left..."
My question is, what's it?
Are they the sounds cried by a drill instructor? You know those "ree", "bup" "bay" just can't be found in a dictionary.
Thank you for your help.

It might have to do with this "bop" song. I couldn't find the lyrics. This is from an online source:
Lionel Hampton had made a record called "Hey Baba Ree Bop" and everybody yelled it and it was when Lionel would jump in the audience and whale his saxophone at everybody with sweat, claps, jumping fools in the aisles, the drummer booming and belaboring on his stage as the whole theater rocked..."Skidilibee-la-bee you, -oo, -e bop she bam, ske too ria--Parasakiliaoolza--menooriastibatiolyait -oon ya koo."