Several programming languages offer syntax shortcuts to deal with the notion of "current" or "topic" variable.

A topic variable is a special variable with a very short name which can also often be omitted.

Demonstrate the utilization and behaviour of the topic variable within the language and explain or demonstrate how the topic variable behaves under different levels of nesting or scope, if this applies, within the language.

For instance you can (but you don't have to) show how the topic variable can be used by assigning the number 



3


{\displaystyle 3}

 to it and then computing its square and square root.




/*REXX program shows something close to a  "topic variable" (for functions/subroutines).*/
parse arg N                                      /*obtain a variable from the cmd line. */
call  squareIt N                                 /*invoke a function to square da number*/
say   result       '  ◄───'                      /*display returned value from the func.*/
exit 0                                           /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
squareIt:  return  arg(1) ** 2                   /*return the square of passed argument.*/