anchor.diff:  // GRAMMAR OF A TYPE INHERITANCE CLAUSE
   
   type_inheritance_clause : ':' type_inheritance_list  ;
  -type_inheritance_list : type_identifier | type_identifier ',' type_inheritance_list  ;
  +type_inheritance_list : type_identifier (',' type_identifier)* ;
   
   // ---------- Lexical Structure -----------
   
  
positive.code: 
  // GRAMMAR OF A GENERIC PARAMETER CLAUSE
  
  generic_parameter_clause : '<' generic_parameter_list requirement_clause?'>'  ;
  generic_parameter_list : generic_parameter | generic_parameter ',' generic_parameter_list  ;
  generic_parameter : type_name | type_name ':' type_identifier | type_name ':' protocol_composition_type  ;
  requirement_clause : 'where' requirement_list  ;
  
negative.code: 
  import_declaration : attributes? 'import' import_kind? import_path  ;
  import_kind : 'typealias' | 'struct' | 'class' | 'enum' | 'protocol' | 'var' | 'func'  ;
  import_path : import_path_identifier | import_path_identifier '.' import_path  ;
  import_path_identifier : identifier | Operator  ;
  
  // GRAMMAR OF A CONSTANT DECLARATION
  