/// Allows AIRs to indicate the names of their columns, for debugging purposes.
/// A default implementation is provided that returns `None`, indicating that
/// column names are not available.
pub trait ColumnsAir {
/// If available, returns the names of columns used in this AIR.
/// If the result is `Some(names)`, `names.len() == air.width()` should always
/// be true.
fn columns(&self) -> Option<Vec<String>> {
None
}
}