+-->-->-->-->.........-->-->-->1,1--5: Runtime error: Aborted
+ \e[0;31mabort\e[0m
+ ^
+,---- Stack trace -- - - -
+| input-22$Sys$main (1,1--5)
+`------------------- - - -
+-->1,1--7: Runtime error: Receiver is null
+ \e[0;31mnil.foo\e[0m
+ ^
+,---- Stack trace -- - - -
+| input-23$Sys$main (1,1--7)
+`------------------- - - -
+-->1,1--28: Runtime error: Abstract method `foo_abstract` called on `Sys`
+ \e[0;31mfun foo_abstract is abstract\e[0m
+ ^
+,---- Stack trace -- - - -
+| input-18$Sys$foo_abstract (1,1--28)
+| input-24$Sys$main (1,1--12)
+`------------------- - - -
+-->1,1--12: Runtime error: Assert failed
+ \e[0;31massert false\e[0m
+ ^
+,---- Stack trace -- - - -
+| input-25$Sys$main (1,1--12)
+`------------------- - - -
+-->1,1--13: Runtime error: Cast failed. Expected `B`, got `A`
+ \e[0;31m(new A).as(B)\e[0m.foo
+ ^
+,---- Stack trace -- - - -
+| input-26$Sys$main (1,1--13)
+`------------------- - - -
+-->1,7--15: Runtime error: Uninitialized attribute _a
+ print(\e[0;31m(new B).a\e[0m)
+ ^
+,---- Stack trace -- - - -
+| input-27$Sys$main (1,7--15)
+`------------------- - - -
+-->1,1--24: Runtime error: NOT YET IMPLEMENTED intern input-19$Sys$foo_intern
+ \e[0;31mfun foo_intern is intern\e[0m
+ ^
+,---- Stack trace -- - - -
+| input-19$Sys$foo_intern (1,1--24)
+| input-28$Sys$main (1,1--10)
+`------------------- - - -
+-->-->Finished