anchor.diff:      -> ^(ALIAS_DECL aliasDeclaration)
       | objectDeclaration
       -> ^(OBJECT_DECL objectDeclaration)
  -    | unionDeclaration
       ;
   
   importDeclaration
  
positive.code:     :   'break'
      ;
  
  CHOICE
      :   'choice'
      ;
   
  CASE
      :   'case'
      ;
  
negative.code:         'alias'!
          typeName
          typeParameters?
          typeConstraints?
          aliasBody
      ;
  
  aliasBody
      : '='! type ';'!
      ;
  
  classDeclaration
  