Function set_argv_skip 

pub fn set_argv_skip(count: usize) -> usize

Says how many leading command-line arguments are the command’s own, and returns the count that was in effect.

candela-vm game.cdlb a b and candela game.cdl a b both put the program’s first argument third, which is the default. A command that spells a verb out first, as candela run game.cdl a b does, has one more of its own to step over and says so here.