Update 2021-02-04-coasters.md

`exportToJSON` no longer exists, replaced with a working snippet using `exportToJSONStream:`

_posts/2021-02-04-coasters.md

@@ -169,13 +169,13 @@ Once I have created the collection, I can save it using the Moose export format
 To do so, I execute the following snippet:
 
 ```st
-model exportToJSON.
+'/my/collection/model.json' asFileReference ensureCreateFile writeStreamDo: [ :stream | model exportToJSONStream: stream ]
 ```
 
 Then I can select where I want to export my model.
 
 To import it back into an image, I use the following code
 
 ```st
-'/my/collection/model.json' asFileReference readStreamDo: [:stream | model := CCModel importFromJSONStream: stream ] 
+'/my/collection/model.json' asFileReference readStreamDo: [ :stream | model := CCModel importFromJSONStream: stream ] 
 ```