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