code: def parse(bin_payload):    
      
      
      message_hash = hexlify(bin_payload)
      if not is_hex( message_hash ):
          log.warning("Not a message hash")
          return None 
  
      if len(message_hash) != 40:
          log.warning("Not a 160-bit hash")
          return None 
  
      return {
         'opcode': 'ANNOUNCE',
         'message_hash': message_hash
      }
docs: Interpret a block's nulldata back into a SHA256.  The first three bytes (2 magic + 1 opcode)
      will not be present in bin_payload.