@arr = (
  {
    person => 'PersonA', 
    place => 'PlaceA', 
    works_for => '', 
    has_assistant => 'PersonC',
  }
  {
    person => 'PersonB', 
    place => 'PlaceB', 
    works_for => '', 
    has_assistant => 'PersonC',
  }
  {
    person => 'PersonC', 
    place => 'PlaceA', 
    works_for => 'PersonA', 
    has_assistant => '',
  }
);