anchor.diff:  selector 
       : ('.' | '^.' | '?.' | '*.') memberName
       | reflectedMember
  -    | (primaryFunctorStart) => primaryFunctor
  +    | (selectorFunctorStart) => selectorFunctor
       | arguments
       | elementSelector
       ;
  
positive.code: //special rule for syntactic predicates
  primaryFunctorStart
      : 'functor' | '(' (declarationStart | ')' '{')
      ;
  
  //special rule for syntactic predicates
  
negative.code:     : functorHeader? formalParameters block
      ;
  
  //a functor expression that can appear inside an expression
  //or as a method argument without the need for parens
  selectorFunctor 
      : functorHeader? formalParameters? block
      ;
  
  //shortcut functor expression that makes the parameter list 
  //optional, but can appear only using the special smalltalk
  //style method protocol
  