anchor.diff:          extendedType?
           satisfiedTypes?
           typeConstraints?
  -        '{' instances? memberOrStatement* '}'
  +        '{' ((instanceStart)=>instances)? memberOrStatement* '}'
       ;
   
   extendedType
  
positive.code:     ;
      
  instances
      : 'instances' instance (',' instance)* (';'|'...')
      ;
  
  instance 
      : /*annotations?*/ memberName arguments?
      ;
  
  typeConstraint
  
negative.code:     
  COMPARE
      :   '<=>'
      ;
      
  INSTANCE
      :   'instance'
      ;
      
  IN
  