anchor.diff:              Gen(S, Contract, TypeName, TypeStack)
       end.
   
  -ubf_command_gen_type(S, Contract, TypeName, TypeStack) ->
  +command_typegen(S, Contract, TypeName, TypeStack) ->
       Fun = fun(TN) -> try_command_typegen(S, Contract, TN, [TypeName|TypeStack]) end,
       Gen =
           fun(TN) ->
  
positive.code: 
  %% qc_statem Callbacks
  -behaviour(qc_statem).
  -export([scenario_gen/0, command_gen/1, command_gen/2]).
  -export([initial_state/1, state_is_sane/1, next_state/3, precondition/2, postcondition/3]).
  -export([setup/0, setup/1, teardown/2, aggregate/1]).
  
  
negative.code:     end.
  
  try_command_typegen(S, Contract, TypeName, TypeStack) ->
      Gen = fun command_typegen/4,
      try
          MOD:command_typegen(Gen, S, Contract, TypeName, TypeStack)
      catch
  