anchor.diff:      // Exercise system
       let result = sut.Relay
       // Verify outcome
  -    Assert.IsType<FilteringSpecimenBuilder>(result)
  +    verify <@ result.GetType() = typeof<FilteringSpecimenBuilder> @>
       // Teardown
   
   [<Fact>]
  
positive.code:     // Exercise system
      sut.Customize(fixtureStub)
      // Verify outcome
      Assert.Empty(customizations)
      // Teardown
  
  
negative.code:     // Exercise system
      sut.Customize(fixtureStub)
      // Verify outcome
      verify <@ Seq.exists ((=) sut.Relay) <| residueCollectors @>
      // Teardown
  
  [<Fact>]
  