anchor.diff:  
   // GRAMMAR OF A PROTOCOL INITIALIZER DECLARATION
   
  -protocol_initializer_declaration : initializer_head generic_parameter_clause? parameter_clause  ;
  +protocol_initializer_declaration
  + : initializer_head generic_parameter_clause? parameter_clause 'throws'?
  + | initializer_head generic_parameter_clause? parameter_clause 'rethrows'
  + ;
   
   // GRAMMAR OF A PROTOCOL SUBSCRIPT DECLARATION
   
  
positive.code: 
  // GRAMMAR OF A METATYPE TYPE
  
  metatype_type : type '.' 'Type' | type '.' 'Protocol';
  
  // GRAMMAR OF A TYPE INHERITANCE CLAUSE
  
  type_inheritance_clause : ':' type_inheritance_list  ;
  type_inheritance_list : type_identifier (',' type_identifier)* ;
  
  // ---------- Lexical Structure -----------
  
  
negative.code: 
  identifier : Identifier | context_sensitive_keyword ;
  
  
  Identifier : Identifier_head Identifier_characters?
   | '`' Identifier_head Identifier_characters? '`'
  