--SEMANTIC---------
Recursivity without end (call_slot).
Line 19 column 35 in Block(.../lib/kernel/block.li):
  - while self:{Boolean} do blk:{} <-
                                   ^

Line 23 column 23 in Block(.../lib/kernel/block.li):
      while self do blk
                       ^
Context:
  ...
Line 19 column 35 in Block(.../lib/kernel/block.li):
  - while self:{Boolean} do blk:{} <-
                                   ^
