private PsiElement performReplace(
      @NotNull final PsiElement declaration, final IntroduceOperation operation) {
    final PyExpression expression = operation.getInitializer();
    final Project project = operation.getProject();
    return new WriteCommandAction<PsiElement>(project, expression.getContainingFile()) {
      protected void run(final Result<PsiElement> result) throws Throwable {
        result.setResult(addDeclaration(operation, declaration));

        PyExpression newExpression = createExpression(project, operation.getName(), declaration);

        if (operation.isReplaceAll()) {
          List<PsiElement> newOccurrences = new ArrayList<PsiElement>();
          for (PsiElement occurrence : operation.getOccurrences()) {
            final PsiElement replaced = replaceExpression(occurrence, newExpression, operation);
            if (replaced != null) {
              newOccurrences.add(replaced);
            }
          }
          operation.setOccurrences(newOccurrences);
        } else {
          final PsiElement replaced = replaceExpression(expression, newExpression, operation);
          operation.setOccurrences(Collections.singletonList(replaced));
        }

        postRefactoring(operation.getElement());
      }
    }.execute().getResultObject();
  }
  protected Collection<String> generateSuggestedNames(PyExpression expression) {
    Collection<String> candidates =
        new LinkedHashSet<String>() {
          @Override
          public boolean add(String s) {
            if (PyNames.isReserved(s)) {
              return false;
            }
            return super.add(s);
          }
        };
    String text = expression.getText();
    final Pair<PsiElement, TextRange> selection =
        expression.getUserData(PyReplaceExpressionUtil.SELECTION_BREAKS_AST_NODE);
    if (selection != null) {
      text = selection.getSecond().substring(text);
    }
    if (expression instanceof PyCallExpression) {
      final PyExpression callee = ((PyCallExpression) expression).getCallee();
      if (callee != null) {
        text = callee.getText();
      }
    }
    if (text != null) {
      candidates.addAll(NameSuggesterUtil.generateNames(text));
    }
    final TypeEvalContext context = TypeEvalContext.userInitiated(expression.getContainingFile());
    PyType type = context.getType(expression);
    if (type != null && type != PyNoneType.INSTANCE) {
      String typeName = type.getName();
      if (typeName != null) {
        if (type.isBuiltin()) {
          typeName = typeName.substring(0, 1);
        }
        candidates.addAll(NameSuggesterUtil.generateNamesByType(typeName));
      }
    }
    final PyKeywordArgument kwArg =
        PsiTreeUtil.getParentOfType(expression, PyKeywordArgument.class);
    if (kwArg != null && kwArg.getValueExpression() == expression) {
      candidates.add(kwArg.getKeyword());
    }

    final PyArgumentList argList = PsiTreeUtil.getParentOfType(expression, PyArgumentList.class);
    if (argList != null) {
      final CallArgumentsMapping result = argList.analyzeCall(PyResolveContext.noImplicits());
      if (result.getMarkedCallee() != null) {
        final PyNamedParameter namedParameter = result.getPlainMappedParams().get(expression);
        if (namedParameter != null) {
          candidates.add(namedParameter.getName());
        }
      }
    }
    return candidates;
  }
 @Nullable
 @Override
 public List<? extends RatedResolveResult> resolveMember(
     @NotNull String name,
     @Nullable PyExpression location,
     @NotNull AccessDirection direction,
     @NotNull PyResolveContext resolveContext) {
   final PsiElement resolved = myImportedModule.resolve();
   if (resolved != null) {
     final PsiFile containingFile = location != null ? location.getContainingFile() : null;
     List<PsiElement> elements =
         Collections.singletonList(
             ResolveImportUtil.resolveChild(resolved, name, containingFile, false, true));
     final PyImportElement importElement = myImportedModule.getImportElement();
     final PyFile resolvedFile = PyUtil.as(resolved, PyFile.class);
     if (location != null
         && importElement != null
         && PyUtil.inSameFile(location, importElement)
         && ResolveImportUtil.getPointInImport(location) == PointInImport.NONE
         && resolved instanceof PsiFileSystemItem
         && (resolvedFile == null
             || !PyUtil.isPackage(resolvedFile)
             || resolvedFile.getElementNamed(name) == null)) {
       final List<PsiElement> importedSubmodules =
           PyModuleType.collectImportedSubmodules((PsiFileSystemItem) resolved, location);
       if (importedSubmodules != null) {
         final Set<PsiElement> imported = Sets.newHashSet(importedSubmodules);
         elements =
             ContainerUtil.filter(
                 elements,
                 new Condition<PsiElement>() {
                   @Override
                   public boolean value(PsiElement element) {
                     return imported.contains(element);
                   }
                 });
       }
     }
     return ResolveImportUtil.rateResults(elements);
   }
   return null;
 }