# File lib/benchmark.rb, line 494
    def format(arg0 = nil, *args)
      fmtstr = (arg0 || FMTSTR).dup
      fmtstr.gsub!(/(%[-+\.\d]*)n/){"#{$1}s" % label}
      fmtstr.gsub!(/(%[-+\.\d]*)u/){"#{$1}f" % utime}
      fmtstr.gsub!(/(%[-+\.\d]*)y/){"#{$1}f" % stime}
      fmtstr.gsub!(/(%[-+\.\d]*)U/){"#{$1}f" % cutime}
      fmtstr.gsub!(/(%[-+\.\d]*)Y/){"#{$1}f" % cstime}
      fmtstr.gsub!(/(%[-+\.\d]*)t/){"#{$1}f" % total}
      fmtstr.gsub!(/(%[-+\.\d]*)r/){"(#{$1}f)" % real}
      arg0 ? Kernel::format(fmtstr, *args) : fmtstr
    end