Task

 verify the version/revision of your currently running (compiler/interpreter/byte-compiler/runtime environment/whatever your language uses) and exit if it is too old.
 check whether the variable "bloop" exists and whether the math-function "abs()" is available and if yes compute abs(bloop).


Extra credit

 Report the number of integer variables in global scope, and their sum.


show logoversion   ; 5.6
if logoversion < 6.0 [print [too old!]]
 
if and [name? "a] [number? :a] [
  print ifelse procedure? "abs [abs :a] [ifelse :a < 0 [minus :a] [:a]]
]