@Override
 public PyType getReferenceType(
     @NotNull PsiElement referenceTarget, TypeEvalContext context, @Nullable PsiElement anchor) {
   if (referenceTarget instanceof PyTargetExpression) {
     final PyTargetExpression target = (PyTargetExpression) referenceTarget;
     if (context.maySwitchToAST(target)) {
       // XXX: Requires switching from stub to AST
       final PyAnnotation annotation = target.getAnnotation();
       if (annotation != null) {
         final PyExpression value = annotation.getValue();
         if (value != null) {
           return getType(value, new Context(context));
         }
         return null;
       }
     }
     final String comment = target.getTypeCommentAnnotation();
     if (comment != null) {
       final PyType type = getStringBasedType(comment, referenceTarget, new Context(context));
       if (type instanceof PyTupleType) {
         final PyTupleExpression tupleExpr =
             PsiTreeUtil.getParentOfType(target, PyTupleExpression.class);
         if (tupleExpr != null) {
           return PyTypeChecker.getTargetTypeFromTupleAssignment(
               target, tupleExpr, (PyTupleType) type);
         }
       }
       return type;
     }
   }
   return null;
 }
 @NotNull
 public QualifiedResolveResult followAssignmentsChain(PyResolveContext resolveContext) {
   PyReferenceExpression seeker = this;
   QualifiedResolveResult ret = null;
   List<PyExpression> qualifiers = new ArrayList<PyExpression>();
   PyExpression qualifier = seeker.getQualifier();
   if (qualifier != null) {
     qualifiers.add(qualifier);
   }
   Set<PsiElement> visited = new HashSet<PsiElement>();
   visited.add(this);
   SEARCH:
   while (ret == null) {
     ResolveResult[] targets = seeker.getReference(resolveContext).multiResolve(false);
     for (ResolveResult target : targets) {
       PsiElement elt = target.getElement();
       if (elt instanceof PyTargetExpression) {
         PsiElement assigned_from = null;
         final PyTargetExpression expr = (PyTargetExpression) elt;
         final TypeEvalContext context = resolveContext.getTypeEvalContext();
         if (context.maySwitchToAST(expr) || expr.getStub() == null) {
           assigned_from = expr.findAssignedValue();
         }
         // TODO: Maybe findAssignedValueByStub() should become a part of the PyTargetExpression
         // interface
         else if (elt instanceof PyTargetExpressionImpl) {
           assigned_from = ((PyTargetExpressionImpl) elt).findAssignedValueByStub(context);
         }
         if (assigned_from instanceof PyReferenceExpression) {
           if (visited.contains(assigned_from)) {
             break;
           }
           visited.add(assigned_from);
           seeker = (PyReferenceExpression) assigned_from;
           if (seeker.getQualifier() != null) {
             qualifiers.add(seeker.getQualifier());
           }
           continue SEARCH;
         } else if (assigned_from != null)
           ret = new QualifiedResolveResultImpl(assigned_from, qualifiers, false);
       } else if (ret == null && elt instanceof PyElement && target.isValidResult()) {
         // remember this result, but a further reference may be the next resolve result
         ret =
             new QualifiedResolveResultImpl(
                 elt, qualifiers, target instanceof ImplicitResolveResult);
       }
     }
     // all resolve results checked, reassignment not detected, nothing more to do
     break;
   }
   if (ret == null) ret = EMPTY_RESULT;
   return ret;
 }
 @Override
 public void visitPyNonlocalStatement(final PyNonlocalStatement node) {
   for (PyTargetExpression var : node.getVariables()) {
     final String name = var.getName();
     final ScopeOwner owner = ScopeUtil.getDeclarationScopeOwner(var, name);
     if (owner == null || owner instanceof PyFile) {
       registerProblem(
           var,
           PyBundle.message("INSP.unbound.nonlocal.variable", name),
           ProblemHighlightType.GENERIC_ERROR_OR_WARNING);
     }
   }
 }
 @Nullable
 private static PyType getTypeFromTargetExpression(
     @NotNull PyTargetExpression expression, @NotNull Context context) {
   // XXX: Requires switching from stub to AST
   final PyExpression assignedValue = expression.findAssignedValue();
   return assignedValue != null ? getTypeForResolvedElement(assignedValue, context) : null;
 }
 @Override
 protected void moveOffsetAfter(boolean success) {
   if (success && (myPanel != null && myPanel.getInitPlace() != InitPlace.SAME_METHOD)
       || myOperation.getInplaceInitPlace() != InitPlace.SAME_METHOD) {
     final AccessToken accessToken =
         ApplicationManager.getApplication().acquireWriteActionLock(getClass());
     try {
       final PyAssignmentStatement initializer =
           PsiTreeUtil.getParentOfType(myTarget, PyAssignmentStatement.class);
       assert initializer != null;
       final Function<String, PyStatement> callback =
           FunctionUtil.<String, PyStatement>constant(initializer);
       final PyClass pyClass = PyUtil.getContainingClassOrSelf(initializer);
       InitPlace initPlace =
           myPanel != null ? myPanel.getInitPlace() : myOperation.getInplaceInitPlace();
       if (initPlace == InitPlace.CONSTRUCTOR) {
         AddFieldQuickFix.addFieldToInit(myProject, pyClass, "", callback);
       } else if (initPlace == InitPlace.SET_UP) {
         addFieldToSetUp(pyClass, callback);
       }
       if (myOperation.getOccurrences().size() > 0) {
         initializer.delete();
       } else {
         final PyExpression copy =
             PyElementGenerator.getInstance(myProject)
                 .createExpressionFromText(
                     LanguageLevel.forElement(myTarget), myTarget.getText());
         initializer.replace(copy);
       }
       initializer.delete();
     } finally {
       accessToken.finish();
     }
   }
 }
 @NotNull
 private static List<PsiElement> tryResolving(
     @NotNull PyExpression expression, @NotNull TypeEvalContext context) {
   final List<PsiElement> elements = Lists.newArrayList();
   if (expression instanceof PyReferenceExpression) {
     final PyReferenceExpression referenceExpr = (PyReferenceExpression) expression;
     final PyResolveContext resolveContext =
         PyResolveContext.noImplicits().withTypeEvalContext(context);
     final PsiPolyVariantReference reference = referenceExpr.getReference(resolveContext);
     final List<PsiElement> resolved = PyUtil.multiResolveTopPriority(reference);
     for (PsiElement element : resolved) {
       if (element instanceof PyFunction) {
         final PyFunction function = (PyFunction) element;
         if (PyUtil.isInit(function)) {
           final PyClass cls = function.getContainingClass();
           if (cls != null) {
             elements.add(cls);
             continue;
           }
         }
       } else if (element instanceof PyTargetExpression) {
         final PyTargetExpression targetExpr = (PyTargetExpression) element;
         // XXX: Requires switching from stub to AST
         final PyExpression assignedValue = targetExpr.findAssignedValue();
         if (assignedValue != null) {
           elements.add(assignedValue);
           continue;
         }
       }
       if (element != null) {
         elements.add(element);
       }
     }
   }
   return !elements.isEmpty() ? elements : Collections.singletonList(expression);
 }
  private void buildFromAttributeDoc() {
    PyClass cls = PsiTreeUtil.getParentOfType(myElement, PyClass.class);
    assert cls != null;
    String type =
        PyUtil.isInstanceAttribute((PyExpression) myElement)
            ? "Instance attribute "
            : "Class attribute ";
    myProlog
        .addItem(type)
        .addWith(TagBold, $().addWith(TagCode, $(((PyTargetExpression) myElement).getName())))
        .addItem(" of class ")
        .addWith(PythonDocumentationProvider.LinkMyClass, $().addWith(TagCode, $(cls.getName())))
        .addItem(BR);

    final String docString = ((PyTargetExpression) myElement).getDocStringValue();
    if (docString != null) {
      addFormattedDocString(myElement, docString, myBody, myEpilog);
    }
  }
 @Override
 protected PsiElement checkLocalScope() {
   return myTarget.getContainingFile();
 }