anchor.diff:  
   function_declaration : function_head function_name generic_parameter_clause? function_signature function_body  ;
   function_head : attributes? declaration_specifiers? 'func'  ;
  -function_name : identifier |  Operator  ;
  +function_name : identifier |  operator  ;
   function_signature : parameter_clauses function_result? ;
   function_result : '->' attributes? type  ;
   function_body : code_block  ;
  
positive.code:  */
  grammar Swift;
  
  top_level : (statement | declaration | expression)* EOF ;
  
  // Statements
  
  
negative.code: 
  Block_comment : '/*' (Block_comment|.)*? '*/' -> channel(HIDDEN) ; // nesting allow
  
  Line_comment : '//' .*? '\n' -> channel(HIDDEN) ;
  