old_contents: 
  '''contains main protocol logic like assembly of proof-of-timeline and parsing deck info'''
  
  from . import paproto
  
  def parse_deckspawn_metainfo(protobuf):
  
      deck = paproto.DeckSpawn()
      deck.ParseFromString(protobuf)
      deck.DiscardUnknownFields() # discard fields not defined by protocol
  
      assert deck.version > 0, {"error": "Deck metainfo incomplete, version can't be 0."}
      assert deck.name is not "", {"error": "Deck metainfo, Deck must have a name."}
      assert deck.number_of_decimals > 0, {"error": '''Deck metainfo, number of decimals
                                           has to be larger than zero.'''}
  
      return {
          "version": deck.version,
          "name": deck.name,
          "issue_mode": deck.issue_mode,
          "number_of_decimals": deck.number_of_decimals
      }
  
  
new_contents: 
  '''contains main protocol logic like assembly of proof-of-timeline and parsing deck info'''
  
  from . import paproto
  
  def parse_deckspawn_metainfo(protobuf):
  
      deck = paproto.DeckSpawn()
      deck.ParseFromString(protobuf)
  
      assert deck.version > 0, {"error": "Deck metainfo incomplete, version can't be 0."}
      assert deck.name is not "", {"error": "Deck metainfo incomplete, Deck must have a name."}
      assert deck.number_of_decimals > 0, {"error": '''Deck metainfo incomplete, number of decimals
                                           has to be larger than zero.'''}
  
      return {
          "version": deck.version,
          "name": deck.name,
          "issue_mode": deck.issue_mode,
          "number_of_decimals": deck.number_of_decimals
      }
  
  
subject: make error messages equal