The two dancers then perform together, each doing his or her own thing.
In fact, it can be performed by dancers of any age.
They are performed by dancers associated with national and cultural groups.
To some degree, that is because of what these dancers perform.
Until last year, no other dancers had performed the roles.
"What I discovered was that dancers perform maybe two weeks a year," he says.
She left the stage for a costume change while her dancers performed.
Since then many ballet companies and dancers have performed the piece.
"We create something that's never been done," he said of the pieces that the dancers perform together.
Only the most successful dancers actually perform these pieces in front of an audience.