anchor.diff:  /// namespace. All top-level functions, typedefs and global variables are added
   /// to this scope.
   ///
  -/// The `parent` of a namespace is `null`.
  +/// The `parent` of a namespace object is `null`.
   class Namespace extends AstNode with Scope {
     Namespace() : super(null);
   
  
positive.code: /// You can parse code into this structure using the `minic.src.parser` library.
  ///
  /// [1]: https://en.wikipedia.org/wiki/Abstract_syntax_tree
  library minic.src.scope;
  
  import 'dart:collection' show LinkedHashMap;
  
  
negative.code: 
    UndefinedNameException(this.identifier);
  }
  
  /// Thrown by [Scope]`.define` if the identifier of the assigned definition
  /// already exists in that scope.
  class NameCollisionException implements Exception {
    /// The definition that already existed in the scope.
    Definition first;
  
    /// The definition that was added last and caused the collision with `first`.
    Definition second;
  
    NameCollisionException(this.first, this.second);
  }
  