- compilation does not always setup the byte_code tree correct (e.g. if one adds a use frame it is likely that everything is messed up - to go on the project seems to be CLEANED and compiled from scratch)
- supplier side for frames: POGs need to be generated as assert-statements
- generate POG for sideeffect-freeness of queries
- BPL_BN_IMPLEMENTATION_WRITER has to be fixed
- inherited FRAMES, confined keyword
- TODOs in BPL_FEATURE_LIST_GENERATOR
- models

- typecheck "confined EXRR": EXPR should be (a subtype of) FRAME
- confined is only allowed in postconditions in commands
- ast_feature_checker_generator create meaningful error, if type of frame_specification is wrong

- types which are declared in the background theory are detected only by the
  class name -> we should handle cluster shadowing

- generics do not work (e. g. attribute c: MY_CELL [STRING]), they crash ballet