Function lower_loop_lane 

pub fn lower_loop_lane(
    source: &str,
    chip: RduChip,
) -> Result<LoopLaneArtifact, String>

Lower the first function of source — a counted range loop — onto chip’s mesh descriptor through the Plasticine lane, anchored to the VM at anchor_params. A program whose first function is not that loop is refused with the lane’s own reason.