anchor.diff:      ;
       
   positionalArguments
  -    : '(' (assignable (',' assignable)*)? ')'
  +    : '(' ( (specialStart) => special | (assignable (',' assignable)*)? ) ')'
  +    ;
  +
  +special
  +    : regularType memberName (containment|specifier)
  +    ;
  +
  +specialStart
  +    : regularType memberName ('in'|'=')
       ;
   
   formalParameters
  
positive.code:     ;
  
  methodExpression
      : implicationExpression (methodOrParameterName specialFunctor)*
      ;
  
  methodOrParameterName
  
negative.code: memberDeclaration
      : voidMethod | methodOrGetter | setter
      ;
  
  //TODO: we would not really need the syntactic predicate
  //here if we leave off recognizing methods vs. attributes
  //until later
  methodOrGetter
      : type memberName ( (typeParameterStart | formalParameterStart) => methodDefinition | attributeDefinition )
      ;
  