code: def sign(self, pairs):
          
          kv = kvform.seqToKV(pairs)
  
          try:
              mac = self._macs[self.assoc_type]
          except KeyError:
              raise ValueError(
                  'Unknown association type: %r' % (self.assoc_type,))
  
          return mac(self.secret, kv)
docs: Generate a signature for a sequence of (key, value) pairs
  
  
          @param pairs: The pairs to sign, in order
  
          @type pairs: sequence of (str, str)
  
  
          @return: The binary signature of this sequence of pairs
  
          @rtype: str