anchor.diff:  
   [source,drl]
   ----
  -rule "Minimize traveling distance"
  +rule "Minimize travelling distance"
   when
      House($d : location.getDistance(cleaner.home)))
   then
  
positive.code: . Smart-ass extra credit: Why does the problem description stipulate that some cleaners don't work full-time?
  What would happen if they all work full-time?
  
  Presume there's `Location` class with a functioning `long getDistance(Location)` method.
  
  ==== Success criteria
  
  
negative.code: 
  ==== Problem description
  
  A cleaning company cleans houses. It needs to match cleaners and houses in a week.
  
  * Each cleaner cleans exactly 1 house per day. He/she cleans it entirely during that day, alone.
  * Each house needs to be cleaned once, at a specified day of the week (determined by the house owner).
  * A cleaner works from Monday to Friday. some cleaners work only 3 days in a week, but the company can chose when.
  * A cleaner travels from his/her home to one house in the morning and travels back in the evening.
  
  Plan a schedule of the cleaning company for an entire week. Minimize the overall travelling distance of the cleaners.
  
  ==== Assignment
  
  