anchor.diff:  // A line of user input in the interactive interpreter
   interpretable
     :	(importDeclaration
  -     | classDeclaration
  +     | classDefinition
        | statement)+
   	;
   
   file
  -	:	namespaceDeclaration? importDeclaration* (classDeclaration | interfaceDeclaration | test)
  +	:	namespaceDeclaration? importDeclaration* (classDefinition | interfaceDefinition | test)
   	;
   
   namespaceDeclaration
  
positive.code: 	-> ^(IMPL qualifiedType)*
  	;
  
  interfaceDeclaration
    : 'interface' TypeIdentifier interfaceBlock
    -> ^(INTERFACE TypeIdentifier interfaceBlock?)
    ;
  
negative.code:   : doc? modifiers? TypeIdentifier VariableIdentifier parameterList
    ;
  
  methodDeclaration
    : methodSignature ';'
    -> ^(METHOD methodSignature)
    ;
  