code: function handleEditorChange(session, document, previousDocument) {
  
          if (!currentModule) {
              currentModule = new TernModule();
          }
          
          return currentModule.handleEditorChange(session, document, previousDocument);
      }
docs: Called each time a new editor becomes active.
  
  @param {Session} session - the active hinting session
  @param {Document} document - the document of the editor that has changed
  @param {?Document} previousDocument - the document of the editor is changing from