Derive Macro ColumnsAir 

#[derive(ColumnsAir)]
{
    // Attributes available to this derive:
    #[columns_via]
}

Derives ColumnsAir for an AIR struct.

#[columns_via(SomeCols<u8, ...>)] selects the column struct whose StructReflectionHelper::struct_reflection() (typically derived via #[derive(StructReflection)]) provides the column names. The reflection is element-type invariant, so any concrete element type works — u8 is just the conventional choice. If the AIR has no columns to reflect, write impl ColumnsAir for X {} by hand instead.