Write a code cleaner which creates variable/object that can clear current workspace when used. Missing semicolon (";") in line returning that "thing" will activate cleaning. Example:

   >> x = 1; y = 2; z = 3;
   >> a = cleaner;
   >> b = a;
   >> who

   Your variables are:
   a  b  x  y  z  

   >> b
   >> who

   Your variables are:
   b

   >> c = b
   >> who

   Your variables are:
   c

   >> z = 7

   z = 
       7

   >> cleaner
   >> who

   Your variables are:
   ans