StdHandler
 

Handle_dbid         -- get the primary identifier
Handle_description  -- get the description
Handle_dbxref       -- get database cross references
Handle_sequence     -- get the sequence information
Handle_features     -- get the features

Handle_hsp          -- get similar search HSPs
  ...
These are composable to build specialized handler 
class BuildSeqRecord(Dispatch.Dispatcher):
    def __init__(self):
        Dispatch.Dispatcher.__init__(self, namespace = Std.NS)
        self.acquire(StdHandler.Handle_dbid(self.add_dbid))
        self.acquire(StdHandler.Handle_sequence(self.add_sequence))
     ...
    def add_sequence(self, (alphabet, seq, gapchar, stopchar)):
        alphabet = alphabet_table.get(alphabet,
                                      Alphabet.single_letter_alphabet)
        self.seq = Seq.Seq(seq, alphabet)
 
.