anchor.diff:              // make entity reference
               let entity = Entity entityAddress
   
  -            // synchronize entity state
  -            World.synchronizeEntityState entityState entity world
  -
               // add entity's state to world
               let world =
                   if World.getEntityExists entity world then
  
positive.code:             World.choose { world with EntityStates = entityStates }
  
          static member private addEntityState entityState (entity : Entity) world =
              World.entityStateAdder entityState entity world
  
          static member private removeEntityState (entity : Entity) world =
  
negative.code: 
              // make entity reference
              let entity = Entity entityAddress
  
              // add entity's state to world
              let world =
  