code: def get_algorithm(algorithm):
      
  
      global _hashes
      if _hashes is None:
          _setup_hashes()
  
      if isinstance(algorithm, (str, unicode)):
          algorithm = dns.name.from_text(algorithm)
  
      if sys.hexversion < 0x02050200 and \
         (algorithm == HMAC_SHA384 or algorithm == HMAC_SHA512):
          raise NotImplementedError("TSIG algorithm " + str(algorithm) +
                                    " requires Python 2.5.2 or later")
  
      try:
          return (algorithm.to_digestable(), _hashes[algorithm])
      except KeyError:
          raise NotImplementedError("TSIG algorithm " + str(algorithm) +
                                    " is not supported")
docs: Returns the wire format string and the hash module to use for the
      specified TSIG algorithm
  
      @rtype: (string, hash constructor)
      @raises NotImplementedError: I{algorithm} is not supported