Given the block ID, and information from what looks like 
   an OP_RETURN transaction that is part of the virtual chain, parse the 
   transaction's OP_RETURN nulldata into a dict.
   
   Return the dict if this is a valid op.
   Return None if not.
   
   NOTE: the virtual chain indexer reserves all keys that start with 'virtualchain_'

def db_parse( block_id, opcode, op_payload, senders, inputs, outputs, fee, db_state=None ):
   """
   Given the block ID, and information from what looks like 
   an OP_RETURN transaction that is part of the virtual chain, parse the 
   transaction's OP_RETURN nulldata into a dict.
   
   Return the dict if this is a valid op.
   Return None if not.
   
   NOTE: the virtual chain indexer reserves all keys that start with 'virtualchain_'
   """
   print "\nreference implementation of db_parse\n"
   return None