anchor.diff:    ;
   
   // 19.1 Static Types
  -type
  +dtype
     : typeName typeArguments?
     ;
   typeName
  
positive.code:   ;
  returnType
    : 'void'
    | type
    ;
  
  functionBody
  
negative.code: 
  // 14 Generics
  typeParameter
    : metadata identifier ('extends' dtype)?
    ;
  typeParameters
    : '<' typeParameter (',' typeParameter)* '>'
  