@NotNull
 private static List<PyGenericType> collectGenericTypes(
     @NotNull PyClass cls, @NotNull Context context) {
   boolean isGeneric = false;
   for (PyClass ancestor : cls.getAncestorClasses(context.getTypeContext())) {
     if (GENERIC_CLASSES.contains(ancestor.getQualifiedName())) {
       isGeneric = true;
       break;
     }
   }
   if (isGeneric) {
     final ArrayList<PyGenericType> results = new ArrayList<>();
     // XXX: Requires switching from stub to AST
     for (PyExpression expr : cls.getSuperClassExpressions()) {
       if (expr instanceof PySubscriptionExpression) {
         final PyExpression indexExpr = ((PySubscriptionExpression) expr).getIndexExpression();
         if (indexExpr != null) {
           for (PsiElement resolved : tryResolving(indexExpr, context.getTypeContext())) {
             final PyGenericType genericType = getGenericType(resolved, context);
             if (genericType != null) {
               results.add(genericType);
             }
           }
         }
       }
     }
     return results;
   }
   return Collections.emptyList();
 }
 @Nullable
 private static PyType getParameterizedType(
     @NotNull PsiElement element, @NotNull Context context) {
   if (element instanceof PySubscriptionExpression) {
     final PySubscriptionExpression subscriptionExpr = (PySubscriptionExpression) element;
     final PyExpression operand = subscriptionExpr.getOperand();
     final PyExpression indexExpr = subscriptionExpr.getIndexExpression();
     final PyType operandType = getType(operand, context);
     if (operandType instanceof PyClassType) {
       final PyClass cls = ((PyClassType) operandType).getPyClass();
       final List<PyType> indexTypes = getIndexTypes(subscriptionExpr, context);
       if (PyNames.TUPLE.equals(cls.getQualifiedName())) {
         if (indexExpr instanceof PyTupleExpression) {
           final PyExpression[] elements = ((PyTupleExpression) indexExpr).getElements();
           if (elements.length == 2 && isEllipsis(elements[1])) {
             return PyTupleType.createHomogeneous(element, indexTypes.get(0));
           }
         }
         return PyTupleType.create(element, indexTypes);
       } else if (indexExpr != null) {
         return new PyCollectionTypeImpl(cls, false, indexTypes);
       }
     }
   }
   return null;
 }
 @Nullable
 private Ref<PyType> getTypeOfProperty(
     @Nullable PyType qualifierType, @NotNull String name, @NotNull TypeEvalContext context) {
   if (qualifierType instanceof PyClassType) {
     final PyClassType classType = (PyClassType) qualifierType;
     PyClass pyClass = classType.getPyClass();
     Property property = pyClass.findProperty(name, true);
     if (property != null) {
       if (classType.isDefinition()) {
         return Ref.<PyType>create(
             PyBuiltinCache.getInstance(pyClass).getObjectType(PyNames.PROPERTY));
       }
       if (AccessDirection.of(this) == AccessDirection.READ) {
         final PyType type = property.getType(context);
         if (type != null) {
           return Ref.create(type);
         }
       }
       return Ref.create();
     }
   } else if (qualifierType instanceof PyUnionType) {
     final PyUnionType unionType = (PyUnionType) qualifierType;
     for (PyType type : unionType.getMembers()) {
       final Ref<PyType> result = getTypeOfProperty(type, name, context);
       if (result != null) {
         return result;
       }
     }
   }
   return null;
 }
 public Property getProperty() {
   final PyClass containingClass = getContainingClass();
   if (containingClass != null) {
     return containingClass.findPropertyByCallable(this);
   }
   return null;
 }
  /**
   * Creates abstract version of each method in each class (does not touch method itself as opposite
   * to {@link #moveMethods(com.jetbrains.python.psi.PyClass, java.util.Collection,
   * com.jetbrains.python.psi.PyClass...)})
   *
   * @param currentFunctions functions to make them abstract
   * @param to classes where abstract method should be created
   */
  private static void makeMethodsAbstract(
      final Collection<PyFunction> currentFunctions, final PyClass... to) {
    final Set<PsiFile> filesToCheckImport = new HashSet<PsiFile>();
    final Set<PyClass> classesToAddMetaAbc = new HashSet<PyClass>();

    for (final PyFunction function : currentFunctions) {
      for (final PyClass destClass : to) {
        final PyFunctionBuilder functionBuilder =
            PyFunctionBuilder.copySignature(function, DECORATORS_MAY_BE_COPIED_TO_ABSTRACT);
        functionBuilder.decorate(PyNames.ABSTRACTMETHOD);
        final LanguageLevel level = LanguageLevel.forElement(destClass);
        PyClassRefactoringUtil.addMethods(
            destClass, false, functionBuilder.buildFunction(destClass.getProject(), level));
        classesToAddMetaAbc.add(destClass);
      }
    }

    // Add ABCMeta to new classes if needed
    for (final PyClass aClass : classesToAddMetaAbc) {
      if (addMetaAbcIfNeeded(aClass)) {
        filesToCheckImport.add(aClass.getContainingFile());
      }
    }

    // Add imports for ABC if needed
    for (final PsiFile file : filesToCheckImport) {
      addImportFromAbc(file, PyNames.ABSTRACTMETHOD);
      addImportFromAbc(file, ABC_META_CLASS);
      PyClassRefactoringUtil.optimizeImports(file); // To remove redundant imports
    }
  }
  /**
   * Looks for two standard decorators to a function, or a wrapping assignment that closely follows
   * it.
   *
   * @return a flag describing what was detected.
   */
  @Nullable
  public Modifier getModifier() {
    final String deconame = getClassOrStaticMethodDecorator();
    if (PyNames.CLASSMETHOD.equals(deconame)) {
      return CLASSMETHOD;
    } else if (PyNames.STATICMETHOD.equals(deconame)) {
      return STATICMETHOD;
    }
    // implicit staticmethod __new__
    final PyClass cls = getContainingClass();
    if (cls != null && PyNames.NEW.equals(getName()) && cls.isNewStyleClass(null)) {
      return STATICMETHOD;
    }
    //
    if (getStub() != null) {
      return getWrappersFromStub();
    }
    final String funcName = getName();
    if (funcName != null) {
      PyAssignmentStatement currentAssignment =
          PsiTreeUtil.getNextSiblingOfType(this, PyAssignmentStatement.class);
      while (currentAssignment != null) {
        final String modifier =
            currentAssignment
                .getTargetsToValuesMapping()
                .stream()
                .filter(
                    pair ->
                        pair.getFirst() instanceof PyTargetExpression
                            && funcName.equals(pair.getFirst().getName()))
                .filter(pair -> pair.getSecond() instanceof PyCallExpression)
                .map(
                    pair ->
                        interpretAsModifierWrappingCall((PyCallExpression) pair.getSecond(), this))
                .filter(interpreted -> interpreted != null && interpreted.getSecond() == this)
                .map(interpreted -> interpreted.getFirst())
                .filter(
                    wrapperName ->
                        PyNames.CLASSMETHOD.equals(wrapperName)
                            || PyNames.STATICMETHOD.equals(wrapperName))
                .findAny()
                .orElse(null);

        if (PyNames.CLASSMETHOD.equals(modifier)) {
          return CLASSMETHOD;
        } else if (PyNames.STATICMETHOD.equals(modifier)) {
          return STATICMETHOD;
        }

        currentAssignment =
            PsiTreeUtil.getNextSiblingOfType(currentAssignment, PyAssignmentStatement.class);
      }
    }
    return null;
  }
 protected String getElementLocation() {
   final PyClass containingClass = getContainingClass();
   if (containingClass != null) {
     return "("
         + containingClass.getName()
         + " in "
         + getPackageForFile(getContainingFile())
         + ")";
   }
   return super.getElementLocation();
 }
 @Nullable
 private static Boolean isOverrides(final PyFunction pyFunction) {
   final PyClass clazz = PyUtil.getContainingClassOrSelf(pyFunction);
   assert clazz != null : "Refactoring called on function, not method: " + pyFunction;
   for (final PyClass parentClass : clazz.getSuperClasses()) {
     final PyFunction parentMethod = parentClass.findMethodByName(pyFunction.getName(), true);
     if (parentMethod != null) {
       return true;
     }
   }
   return null;
 }
 /**
  * Looks for two standard decorators to a function, or a wrapping assignment that closely follows
  * it.
  *
  * @return a flag describing what was detected.
  */
 @Nullable
 public Modifier getModifier() {
   String deconame = getClassOrStaticMethodDecorator();
   if (PyNames.CLASSMETHOD.equals(deconame)) {
     return CLASSMETHOD;
   } else if (PyNames.STATICMETHOD.equals(deconame)) {
     return STATICMETHOD;
   }
   // implicit staticmethod __new__
   PyClass cls = getContainingClass();
   if (cls != null && PyNames.NEW.equals(getName()) && cls.isNewStyleClass()) {
     return STATICMETHOD;
   }
   //
   if (getStub() != null) {
     return getWrappersFromStub();
   }
   String func_name = getName();
   if (func_name != null) {
     PyAssignmentStatement assignment =
         PsiTreeUtil.getNextSiblingOfType(this, PyAssignmentStatement.class);
     if (assignment != null) {
       for (Pair<PyExpression, PyExpression> pair : assignment.getTargetsToValuesMapping()) {
         PyExpression value = pair.getSecond();
         if (value instanceof PyCallExpression) {
           PyExpression target = pair.getFirst();
           if (target instanceof PyTargetExpression && func_name.equals(target.getName())) {
             Pair<String, PyFunction> interpreted =
                 interpretAsModifierWrappingCall((PyCallExpression) value, this);
             if (interpreted != null) {
               PyFunction original = interpreted.getSecond();
               if (original == this) {
                 String wrapper_name = interpreted.getFirst();
                 if (PyNames.CLASSMETHOD.equals(wrapper_name)) {
                   return CLASSMETHOD;
                 } else if (PyNames.STATICMETHOD.equals(wrapper_name)) {
                   return STATICMETHOD;
                 }
               }
             }
           }
         }
       }
     }
   }
   return null;
 }
 @Nullable
 @Override
 public String getQualifiedName() {
   String name = getName();
   if (name == null) {
     return null;
   }
   PyClass containingClass = getContainingClass();
   if (containingClass != null) {
     return containingClass.getQualifiedName() + "." + name;
   }
   if (PsiTreeUtil.getStubOrPsiParent(this) instanceof PyFile) {
     VirtualFile virtualFile = getContainingFile().getVirtualFile();
     if (virtualFile != null) {
       final String packageName =
           QualifiedNameFinder.findShortestImportableName(this, virtualFile);
       return packageName + "." + name;
     }
   }
   return null;
 }
 // TODO: Copy/Paste with PyClass.getMeta..
 private static boolean addMetaAbcIfNeeded(@NotNull final PyClass aClass) {
   final PsiFile file = aClass.getContainingFile();
   final PyType type = aClass.getMetaClassType(TypeEvalContext.userInitiated(file));
   if (type != null) {
     return false; // User already has metaclass. He probably knows about metaclasses, so we should
                   // not add ABCMeta
   }
   final LanguageLevel languageLevel = LanguageLevel.forElement(aClass);
   if (languageLevel
       .isPy3K()) { // TODO: Copy/paste, use strategy because we already has the same check in
                    // #couldBeAbstract
     // Add (metaclass= for Py3K
     PyClassRefactoringUtil.addSuperClassExpressions(
         aClass.getProject(),
         aClass,
         null,
         Collections.singletonList(Pair.create(PyNames.METACLASS, ABC_META_CLASS)));
   } else {
     // Add __metaclass__ for Py2
     PyClassRefactoringUtil.addClassAttributeIfNotExist(
         aClass, PyNames.DUNDER_METACLASS, ABC_META_CLASS);
   }
   return true;
 }
 @NotNull
 @Override
 protected List<PyElement> getMembersCouldBeMoved(@NotNull final PyClass pyClass) {
   return Lists.<PyElement>newArrayList(filterNameless(Arrays.asList(pyClass.getMethods())));
 }
 @Override
 public boolean hasConflict(@NotNull final PyFunction member, @NotNull final PyClass aClass) {
   return NamePredicate.hasElementWithSameName(member, Arrays.asList(aClass.getMethods()));
 }