anchor.diff:  
   Enforcing
   
  -[source,bash]
  +[source,ruby]
   ----
   RSpec.describe MyClass do
     ...
  
positive.code: 
  Enforcing
  
  [source,bash]
  ----
  expect(calculator.compute(line_item)).to eq(5)
  ----
  
  over
  
  [source,bash]
  ----
  calculator.compute(line_item).should == 5
  ----
  
negative.code: 
  over
  
  [source,ruby]
  ----
  describe MyClass do
    ...
  