internal IdentifierName(IdentifierNameSyntax syntax, Package containingPackage, DeclarationReference declaration)
     : base(syntax, containingPackage)
 {
     Declaration = declaration;
 }
 public static LookupResult Good(DeclarationReference declaration)
 {
     Requires.NotNull(declaration, nameof(declaration));
     return new ViableResult(declaration);
 }
 public ViableResult(DeclarationReference declaration)
 {
     Requires.NotNull(declaration, nameof(declaration));
     symbols = new List<DeclarationReference>() { declaration };
 }