anchor.diff:  
   type
       : qualifiedTypeName ( (typeParameterStart) => typeArguments )?
  +    | 'subtype'
       ;
   
   annotations
  
positive.code:     :   'nonempty'
      ;
  
  PRODUCE
      :   'produce'
      ;
  
  RETURN
      :   'return'
  
negative.code:     ;
  
  functionalMemberDefinition
      : memberParameters* block
      //allow omission of braces:
      /*: ( (memberParameterStart) => memberParameters )? 
        ( ('{') => block | implicationExpression ';' )*/
  