anchor.diff:      //| existsCondition
       ;
   
  +extraFormalParameters
  +    : extraFormalParameter*
  +    -> ^(FORMAL_PARAMETER_LIST ^(FORMAL_PARAMETER formalParameter)*)
  +    ;
  +
   formalParameters
       : '(' (formalParameter (',' formalParameter)*)? ')'
       -> ^(FORMAL_PARAMETER_LIST ^(FORMAL_PARAMETER formalParameter)*)
  
positive.code:     ;
  
  memberParameters
      : typeParameters? formalParameters+ typeConstraints?
      ;
  
  //TODO: should we allow the shortcut style of method
  
negative.code:         typeName
          typeParameters?
          formalParameters
          extraFormalParameters
          extendedType?
          satisfiedTypes?
          typeConstraints?
  