anchor.diff:  // BSD-style license that can be found in the LICENSE file.
   
   library fasta.verifier;
  +
  +import 'package:front_end/src/fasta/type_inference/type_schema.dart'
  +    show TypeSchemaVisitor, UnknownType;
   
   import 'package:kernel/ast.dart'
       show
  
positive.code:   @override
    problem(TreeNode node, String details) {
      VerificationError error = new VerificationError(context, node, details);
      printUnexpected(Uri.parse(fileUri), node.fileOffset, "$error");
      errors.add(error);
    }
  
  
negative.code:   visitInvalidInitializer(InvalidInitializer node) {
      problem(node, "Invalid initializer.");
    }
  
    @override
    visitUnknownType(UnknownType node) {
      // Note: we can't pass [node] to [problem] because it's not a [TreeNode].
      problem(null, "Unexpected appearance of the unknown type.");
    }
  }
  