anchor.diff:  
   NOTE: By default, Asciidoctor.js will determine the I/O module upon the runtime environment.
   
  -If you want to explicitly define the I/O module, you can specify the attribute `runtime.ioModule` when instantiating Asciidoctor.js: 
  +If you want to explicitly define the I/O module, you can specify the attribute `runtime.ioModule` when instantiating Asciidoctor.js:
   
   [source,javascript]
   ----
  
positive.code: 
  Both registry have a `[shout]` block extension registered with a specific implementation.
  
  The first block extension is registered in the `registryA` and will transform the text to uppercase. 
  The other one is registered in the `registryB` and will replace `.` by `{nbsp}!!!`.
  
negative.code: 
  NOTE: By default, Asciidoctor.js will try his best to automatically detect the runtime environment.
  
  If you want to explicitly define the runtime environment, you can use a `runtime` configuration object when instantiating Asciidoctor.js:
  
  [source,javascript]
  ----
  const asciidoctor = require('asciidoctor.js')({
    runtime: {
      platform: 'browser',
      engine: 'v8',
      framework: 'webextensions'
    }
  });
  