anchor.diff:  formalParameterStart
       : '(' (declarationStart | ')')
       ;
  -
  -//special rule for syntactic predicates
  -functorStart
  -    : 'op' | formalParameterStart
  -    ;
  -
  -//special rule for syntactic predicates
  -/*primaryFunctorStart
  -    : 'op' | '(' (declarationStart | ')' '{')
  -    ;*/
   
   //special rule for syntactic predicates
   declarationStart
  
positive.code:     ;
  
  assignable 
      : (functorStart) => functor
      | reference
      | reflectedLiteral
      | expression
      ;
  
  
negative.code:         |   '{'
          |   '}' 
          )          
      ;
  
  WS  
  