anchor.diff:  
       static member private setBodyEnabled (setBodyEnabledMessage : SetBodyEnabledMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue setBodyEnabledMessage.PhysicsId with
  -        | (true, body) -> body.Enabled <- setBodyEnabledMessage.Enabled
  +        | (true, (_, body)) -> body.Enabled <- setBodyEnabledMessage.Enabled
           | (false, _) -> Log.debug ("Could not set enabled of non-existent body with PhysicsId = " + scstring setBodyEnabledMessage.PhysicsId + "'.")
   
       static member private setBodyPosition (setBodyPositionMessage : SetBodyPositionMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue setBodyPositionMessage.PhysicsId with
  -        | (true, body) -> body.Position <- FarseerPhysicsEngine.toPhysicsV2 setBodyPositionMessage.Position
  +        | (true, (_, body)) -> body.Position <- FarseerPhysicsEngine.toPhysicsV2 setBodyPositionMessage.Position
           | (false, _) -> Log.debug ("Could not set position of non-existent body with PhysicsId = " + scstring setBodyPositionMessage.PhysicsId + "'.")
   
       static member private setBodyRotation (setBodyRotationMessage : SetBodyRotationMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue setBodyRotationMessage.PhysicsId with
  -        | (true, body) -> body.Rotation <- setBodyRotationMessage.Rotation
  +        | (true, (_, body)) -> body.Rotation <- setBodyRotationMessage.Rotation
           | (false, _) -> Log.debug ("Could not set rotation of non-existent body with PhysicsId = " + scstring setBodyRotationMessage.PhysicsId + "'.")
   
       static member private setBodyAngularVelocity (setBodyAngularVelocityMessage : SetBodyAngularVelocityMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue setBodyAngularVelocityMessage.PhysicsId with
  -        | (true, body) -> body.AngularVelocity <- setBodyAngularVelocityMessage.AngularVelocity
  +        | (true, (_, body)) -> body.AngularVelocity <- setBodyAngularVelocityMessage.AngularVelocity
           | (false, _) -> Log.debug ("Could not set angular velocity of non-existent body with PhysicsId = " + scstring setBodyAngularVelocityMessage.PhysicsId + "'.")
   
       static member private applyBodyAngularImpulse (applyBodyAngularImpulseMessage : ApplyBodyAngularImpulseMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue applyBodyAngularImpulseMessage.PhysicsId with
  -        | (true, body) -> body.ApplyAngularImpulse (applyBodyAngularImpulseMessage.AngularImpulse)
  +        | (true, (_, body)) -> body.ApplyAngularImpulse (applyBodyAngularImpulseMessage.AngularImpulse)
           | (false, _) -> Log.debug ("Could not apply angular impulse to non-existent body with PhysicsId = " + scstring applyBodyAngularImpulseMessage.PhysicsId + "'.")
   
       static member private setBodyLinearVelocity (setBodyLinearVelocityMessage : SetBodyLinearVelocityMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue setBodyLinearVelocityMessage.PhysicsId with
  -        | (true, body) -> body.LinearVelocity <- FarseerPhysicsEngine.toPhysicsV2 setBodyLinearVelocityMessage.LinearVelocity
  +        | (true, (_, body)) -> body.LinearVelocity <- FarseerPhysicsEngine.toPhysicsV2 setBodyLinearVelocityMessage.LinearVelocity
           | (false, _) -> Log.debug ("Could not set linear velocity of non-existent body with PhysicsId = " + scstring setBodyLinearVelocityMessage.PhysicsId + "'.")
   
       static member private applyBodyLinearImpulse (applyBodyLinearImpulseMessage : ApplyBodyLinearImpulseMessage) physicsEngine =
           match physicsEngine.Bodies.TryGetValue applyBodyLinearImpulseMessage.PhysicsId with
  -        | (true, body) -> body.ApplyLinearImpulse (FarseerPhysicsEngine.toPhysicsV2 applyBodyLinearImpulseMessage.LinearImpulse)
  +        | (true, (_, body)) -> body.ApplyLinearImpulse (FarseerPhysicsEngine.toPhysicsV2 applyBodyLinearImpulseMessage.LinearImpulse)
           | (false, _) -> Log.debug ("Could not apply linear impulse to non-existent body with PhysicsId = " + scstring applyBodyLinearImpulseMessage.PhysicsId + "'.")
   
       static member private applyBodyForce applyBodyForceMessage physicsEngine =
           match physicsEngine.Bodies.TryGetValue applyBodyForceMessage.PhysicsId with
  -        | (true, body) -> body.ApplyForce (FarseerPhysicsEngine.toPhysicsV2 applyBodyForceMessage.Force)
  +        | (true, (_, body)) -> body.ApplyForce (FarseerPhysicsEngine.toPhysicsV2 applyBodyForceMessage.Force)
           | (false, _) -> Log.debug ("Could not apply force to non-existent body with PhysicsId = " + scstring applyBodyForceMessage.PhysicsId + "'.")
   
       static member private handlePhysicsMessage physicsEngine physicsMessage =
  
positive.code:         physicsEngine.IntegrationMessages.Add integrationMessage
  
      static member private getBodyContacts physicsId physicsEngine =
          let body = physicsEngine.Bodies.[physicsId]
          let contacts = List<Contact> ()
          let mutable current = body.ContactList
          while current <> null do
  
negative.code:                           Position = FarseerPhysicsEngine.toPixelV2 body.Position
                            Rotation = body.Rotation }
                  physicsEngine.IntegrationMessages.Add bodyTransformMessage
                  
      static member applyGravity physicsStepAmount physicsEngine =
          for (gravityScale, body) in physicsEngine.Bodies.Values do
              let linearVelocity = body.LinearVelocity + physicsEngine.PhysicsContext.Gravity * Common.Vector2 (0.0f, gravityScale) * physicsStepAmount
              body.LinearVelocity <- linearVelocity
  
      /// Make a physics engine.
      static member make gravity =
  