anchor.diff:  
   ==== Problem description
   
  -A cleaner company cleans houses. It needs to match cleaners and houses in a week.
  +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.
  -* All houses needs to be cleaned once, at a specified day of the week (determined by the house owner).
  +* 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 traveling distance of the cleaners.
  +Plan a schedule of the cleaning company for an entire week. Minimize the overall travelling distance of the cleaners.
   
   ==== Assignment
   
  
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: 
  [source,drl]
  ----
  rule "Minimize travelling distance"
  when
     House($d : location.getDistance(cleaner.home)))
  then
  