anchor.diff:          , pubkey/1
           , balance/1
           , height/1
  +        , nonce/1
           , owner/1
           , vm_version/1
           , code/1
  
positive.code:     #contract{ pubkey     = Pubkey
               , balance    = Balance
               , height     = Height
               , owner      = Owner
               , vm_version = VmVersion
               , code       = Code
  
negative.code:         pubkey     :: pubkey(),
          balance    :: amount(),
          height     :: height(),
          nonce      :: non_neg_integer(),
          %% Contract-specific fields
          owner      :: pubkey(),
          vm_version :: vm_version(),
  