Introspection
You are encouraged to solve this task according to the task description, using any language you may know.
This task asks to
- 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).
Perl
Interpreter: Perl 5.x
require v5.6.1; # run time version check require 5.6.1; # ditto require 5.006_001; # ditto; preferred for backwards compatibility
Tcl
package require Tcl 8.2 ; # throws an error if older
if {[info exists bloop] && [llength [info functions abs]]} {
puts [expr abs($bloop)]
}