def convert(data)
      Open3.popen3(command) do |stdin, stdout, stderr| 
        stdin.puts(data)
        stdin.close
        output = stdout.read
        error = stderr.read
        raise ConversionError, error unless error.empty?
        return output.strip
      end
    rescue Errno::ENOENT
      raise NoExecutableError, "Can't find the '#{executable}' executable."
    end
def convert(data)
      Open3.popen3(command) do |stdin, stdout, stderr| 
        stdin.puts(data)
        stdin.close
        output = stdout.read
        error = stderr.read
        raise ConversionError, error unless error.empty?
        return output.strip
      end
    rescue Errno::ENOENT
      raise NoExecutableError, "Can't find the '#{executable}' executable."
    end
Convert `data` between formats.
 @return [String] the converted data