traceCmd :: Worker -> ControlPacket -> IO [TraceRecord]
traceCmd worker pkt =
    do mustBeThawed "traceCmd" worker
       (ResponsePacket _ args) <- sendWorkerCommand worker pkt
       return $ ancillaryDataToTrace args
traceCmd :: Worker -> ControlPacket -> IO [TraceRecord]
traceCmd worker pkt =
    do mustBeThawed "traceCmd" worker
       (ResponsePacket _ args) <- sendWorkerCommand worker pkt
       return $ ancillaryDataToTrace args
traceCmd worker pkt =
    do mustBeThawed "traceCmd" worker
       (ResponsePacket _ args) <- sendWorkerCommand worker pkt
       return $ ancillaryDataToTrace args