$ python3 fpgaperf.py --toolchain nextpnr-xilinx --project blinky --board arty
Writing to build/blinky_nextpnr-xilinx_xc7_a35tcsg324-1_arty_xdc_carry-n
Traceback (most recent call last):
  File "fpgaperf.py", line 404, in <module>
    main()
  File "fpgaperf.py", line 399, in main
    build_type=args.build_type
  File "fpgaperf.py", line 203, in run
    t.run()
  File "/home/dusty/src/fpga-tool-perf/symbiflow.py", line 540, in run
    self.add_runtimes()
  File "/home/dusty/src/fpga-tool-perf/symbiflow.py", line 703, in add_runtimes
    synth_times = self.get_yosys_runtimes(yosys_log)
  File "/home/dusty/src/fpga-tool-perf/symbiflow.py", line 653, in get_yosys_runtimes
    time = float(usr_time) + float(sys_time)
ValueError: could not convert string to float: 'of'