Function write_compact_vcd 

pub fn write_compact_vcd(
    path: &Path,
    scope: &str,
    state_width: usize,
    aux_name: &str,
    aux_width: usize,
    events: &[TraceEvent],
    total_ticks: u64,
) -> Result<()>

Write a small standards-compliant VCD from sparse trace events.