anchor.diff:      ;
   
   initializers
  -    :    ':' superCallOrFieldInitializer (',' superCallOrFieldInitializer)*
  -    ;
  -
  -superCallOrFieldInitializer
  +    :    ':' initializerListEntry (',' initializerListEntry)*
  +    ;
  +
  +initializerListEntry
       :    SUPER arguments
       |    SUPER '.' identifier arguments
       |    fieldInitializer
  -    |    assertClause
  +    |    assertion
       ;
   
   fieldInitializer
  -    :    (THIS '.')? identifier '=' conditionalExpression cascadeSequence?
  +    :    (THIS '.')? identifier '=' initializerExpression
  +    ;
  +
  +initializerExpression
  +    :    conditionalExpression
  +    |    cascade
       ;
   
   factoryConstructorSignature
  
positive.code: 
  metadatum
      :    constructorDesignation arguments
      |    qualified
      ;
  
  expression
      :    functionExpression
      |    throwExpression
      |    assignableExpression assignmentOperator expression
      |    conditionalExpression cascadeSequence?
      ;
  
  expressionWithoutCascade
  
negative.code:     :    label expression
      ;
  
  cascade
      :     cascade '..' cascadeSection
      |     conditionalExpression ('?..' | '..') cascadeSection
      ;
  
  cascadeSection
      :    cascadeSelector cascadeSectionTail
      ;
  
  cascadeSelector
      :    '[' expression ']'
      |    identifier
      ;
  
  cascadeSectionTail
  