DEFINE_string(map_type,"identity","Map operation: one of \"arc_sum\", \"arc_unique\", ""\"identity\", \"input_epsilon\", \"invert\", \"output_epsilon\", ""\"plus (--weight)\", \"power (--power)\", \"quantize (--delta)\", ""\"rmweight\", \"superfinal\", \"times (--weight)\", ""\"to_log\", \"to_log64\", \"to_std\"")