def purge
      output.each do |file, format|
        if File.exist?(file)
          rm(file)
          report "Removed #{file}"
        end
      end
    end
def purge
      output.each do |file, format|
        if File.exist?(file)
          rm(file)
          report "Removed #{file}"
        end
      end
    end
Remove output files.

 @return [void]