anchor.diff:  methodParameters
       : 
           typeParameters? 
  -        formalParameters+ 
  -        extraFormalParameters? 
  +        parameters+ 
  +        extraParameters? 
           metatypes? 
           typeConstraints?
       ;
  
positive.code:     ;
  
  variable
      : inferrableType memberName formalParameters*
      -> ^(VARIABLE inferrableType memberName formalParameters*)
      ;
  
  // Lexer
  
negative.code:     : '=' declarationStart
      ;
  
  extraParameter
      : formalParameterType parameterName parameters*
      ;
  
  formalParameterType
  