anchor.diff:            constant_update_2018 ?? IsEnabledByDefault.constant_update_2018,
             set_literals ?? IsEnabledByDefault.set_literals,
             non_nullable ?? IsEnabledByDefault.non_nullable,
  -          spread_collections ?? IsEnabledByDefault.spread_collections,
             control_flow_collections ??
                 IsEnabledByDefault.control_flow_collections,
  +          spread_collections ?? IsEnabledByDefault.spread_collections,
           ];
   
     /// Decodes the strings given in [flags] into a representation of the set of
  
positive.code:   /// Current state for the flag "constant-update-2018"
    bool get constant_update_2018 => _enableFlags[0];
  
    /// Current state for the flag "non-nullable"
    bool get non_nullable => _enableFlags[2];
  
  
negative.code:   bool get set_literals => _enableFlags[1];
  
    /// Current state for the flag "spread_collections"
    bool get spread_collections => _enableFlags[4];
  
    /// Queries whether the given [feature] is enabled or disabled.
    bool isEnabled(ExperimentalFeature feature) => feature.isExpired
  