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.


(unless (>= (version T) (3 0 1))       # Check version (only in the 64-bit version)
   (bye) )
 
# (setq bloop -7)                      # Uncomment this to get the output '7'
 
(and
   (num? bloop)                        # When 'bloop' is bound to a number
   (getd 'abs)                         # and 'abs' defined as a function
   (println (abs bloop)) )             # then print the absolute value