diff --git a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
index 321532cf7c7..def400042b3 100644
--- a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
+++ b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
@@ -122,6 +122,18 @@ private val tailrecLoweringPhase = makeWasmModulePhase(
     description = "Replace `tailrec` call sites with equivalent loop"
 )
 
+private val complexExternalDeclarationsToTopLevelFunctionsLowering = makeWasmModulePhase(
+    ::ComplexExternalDeclarationsToTopLevelFunctionsLowering,
+    name = "ComplexExternalDeclarationsToTopLevelFunctionsLowering",
+    description = "Lower complex external declarations to top-level functions",
+)
+
+private val complexExternalDeclarationsUsagesLowering = makeWasmModulePhase(
+    ::ComplexExternalDeclarationsUsageLowering,
+    name = "ComplexExternalDeclarationsUsageLowering",
+    description = "Lower usages of complex external declarations",
+)
+
 private val jsInteropFunctionsLowering = makeWasmModulePhase(
     ::JsInteropFunctionsLowering,
     name = "JsInteropFunctionsLowering",
@@ -532,6 +544,9 @@ val wasmPhases = NamedCompilerPhase(
             delegateToPrimaryConstructorLoweringPhase then
             // Common prefix ends
 
+            complexExternalDeclarationsToTopLevelFunctionsLowering then
+            complexExternalDeclarationsUsagesLowering then
+
             jsInteropFunctionsLowering then
             jsInteropFunctionCallsLowering then
 
diff --git a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/DeclarationGenerator.kt b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/DeclarationGenerator.kt
index 10fb96205d0..93f091514d4 100644
--- a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/DeclarationGenerator.kt
+++ b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/DeclarationGenerator.kt
@@ -36,6 +36,10 @@ class DeclarationGenerator(val context: WasmModuleCodegenContext) : IrElementVis
         error("Unexpected element of type ${element::class}")
     }
 
+    override fun visitProperty(declaration: IrProperty) {
+        require(declaration.isExternal)
+    }
+
     override fun visitTypeAlias(declaration: IrTypeAlias) {
         // Type aliases are not material
     }
diff --git a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/ComplexExternalDeclarationsToTopLevelFunctionsLowering.kt b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/ComplexExternalDeclarationsToTopLevelFunctionsLowering.kt
new file mode 100644
index 00000000000..bed26587b12
--- /dev/null
+++ b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/ComplexExternalDeclarationsToTopLevelFunctionsLowering.kt
@@ -0,0 +1,301 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.backend.wasm.lower
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.backend.common.FileLoweringPass
+import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
+import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.backend.js.utils.getJsNameOrKotlinName
+import org.jetbrains.kotlin.ir.backend.js.utils.realOverrideTarget
+import org.jetbrains.kotlin.ir.builders.declarations.addValueParameter
+import org.jetbrains.kotlin.ir.builders.declarations.buildFun
+import org.jetbrains.kotlin.ir.builders.irCallConstructor
+import org.jetbrains.kotlin.ir.builders.irString
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
+import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.visitors.*
+import org.jetbrains.kotlin.name.Name
+import java.lang.StringBuilder
+
+/**
+ * Lower complex external declarations to top-level functions:
+ *   - Property accessors
+ *   - Member functions
+ *   - Class constructors
+ *   - Object declarations
+ *   - Class instance checks
+ */
+class ComplexExternalDeclarationsToTopLevelFunctionsLowering(val context: WasmBackendContext) : FileLoweringPass {
+    lateinit var currentFile: IrFile
+    val addedDeclarations = mutableListOf<IrDeclaration>()
+
+    val externalFunToTopLevelMapping =
+        context.mapping.wasmNestedExternalToNewTopLevelFunction
+
+    val externalObjectToGetInstanceFunction =
+        context.mapping.wasmExternalObjectToGetInstanceFunction
+
+    override fun lower(irFile: IrFile) {
+        currentFile = irFile
+        for (declaration in irFile.declarations) {
+            if (declaration.isEffectivelyExternal()) {
+                processExternalDeclaration(declaration)
+            }
+        }
+        irFile.declarations += addedDeclarations
+        addedDeclarations.clear()
+    }
+
+    fun processExternalDeclaration(declaration: IrDeclaration) {
+        declaration.acceptVoid(object : IrElementVisitorVoid {
+            override fun visitElement(element: IrElement) {
+                error("Unknown external element ${element::class}")
+            }
+
+            override fun visitValueParameter(declaration: IrValueParameter) {
+            }
+
+            override fun visitClass(declaration: IrClass) {
+                declaration.acceptChildrenVoid(this)
+                lowerExternalTopLevelClass(declaration)
+            }
+
+            override fun visitProperty(declaration: IrProperty) {
+                processExternalProperty(declaration)
+            }
+
+            override fun visitConstructor(declaration: IrConstructor) {
+                processExternalConstructor(declaration)
+            }
+
+            override fun visitSimpleFunction(declaration: IrSimpleFunction) {
+                processExternalSimpleFunction(declaration)
+            }
+        })
+    }
+
+    fun lowerExternalTopLevelClass(klass: IrClass) {
+        if (klass.kind == ClassKind.OBJECT)
+            generateExternalObjectInstanceGetter(klass)
+
+        if (klass.kind != ClassKind.INTERFACE)
+            generateInstanceCheckForExternalClass(klass)
+    }
+
+    fun processExternalProperty(property: IrProperty) {
+        if (property.isFakeOverride)
+            return
+
+        val propName: String =
+            property.getJsNameOrKotlinName().identifier
+
+        property.getter?.let { getter ->
+            val dispatchReceiver = getter.dispatchReceiverParameter
+            val jsCode =
+                if (dispatchReceiver == null)
+                    "() => $propName"
+                else
+                    "(_this) => _this.$propName"
+
+            val res = createExternalJsFunction(
+                property.name,
+                "_\$external_prop_getter",
+                resultType = getter.returnType,
+                jsCode = jsCode
+            )
+
+            if (dispatchReceiver != null) {
+                res.addValueParameter("_this", dispatchReceiver.type)
+            }
+
+            externalFunToTopLevelMapping[getter] = res
+        }
+
+        property.setter?.let { setter ->
+            val dispatchReceiver = setter.dispatchReceiverParameter
+            val jsCode =
+                if (dispatchReceiver == null)
+                    "(v) => $propName = v"
+                else
+                    "(_this, v) => _this.$propName = v"
+
+            val res = createExternalJsFunction(
+                property.name,
+                "_\$external_prop_setter",
+                resultType = setter.returnType,
+                jsCode = jsCode
+            )
+
+            if (dispatchReceiver != null) {
+                res.addValueParameter("_this", dispatchReceiver.type)
+            }
+            res.addValueParameter("v", setter.valueParameters[0].type)
+
+            externalFunToTopLevelMapping[setter] = res
+        }
+    }
+
+    private fun StringBuilder.appendExternalClassReference(klass: IrClass) {
+        val parent = klass.parent
+        if (parent is IrClass) {
+            appendExternalClassReference(parent)
+            append('.')
+        }
+        append(klass.getJsNameOrKotlinName())
+    }
+
+    fun processExternalConstructor(constructor: IrConstructor) {
+        val klass = constructor.constructedClass
+        val jsCode = buildString {
+            append("(")
+            appendParameterList(constructor.valueParameters.size)
+            append(") => new ")
+            appendExternalClassReference(klass)
+            append("(")
+            appendParameterList(constructor.valueParameters.size)
+            append(")")
+        }
+
+        val res = createExternalJsFunction(
+            klass.name,
+            "_\$external_constructor",
+            resultType = klass.defaultType,
+            jsCode = jsCode
+        )
+
+        constructor.valueParameters.forEach { res.addValueParameter(it.name, it.type) }
+        externalFunToTopLevelMapping[constructor] = res
+    }
+
+    fun processExternalSimpleFunction(function: IrSimpleFunction) {
+        if (function.parent is IrPackageFragment) return
+        val jsName = function.getJsNameOrKotlinName()
+        val dispatchReceiver = function.dispatchReceiverParameter
+        require(dispatchReceiver != null) {
+            "Non top-level external function w/o dispatchReceiverParameter: ${function.fqNameWhenAvailable}"
+        }
+
+        val jsCode = buildString {
+            append("(_this, ")
+            appendParameterList(function.valueParameters.size)
+            append(") => _this.")
+            append(jsName)
+            append("(")
+            appendParameterList(function.valueParameters.size)
+            append(")")
+        }
+        val res = createExternalJsFunction(
+            function.name,
+            "_\$external_member_fun",
+            resultType = function.returnType,
+            jsCode = jsCode
+        )
+        res.addValueParameter("_this", dispatchReceiver.type)
+        function.valueParameters.forEach { res.addValueParameter(it.name, it.type) }
+
+        externalFunToTopLevelMapping[function] = res
+    }
+
+    fun generateExternalObjectInstanceGetter(obj: IrClass) {
+        context.mapping.wasmExternalObjectToGetInstanceFunction[obj] = createExternalJsFunction(
+            obj.name,
+            "_\$external_object_getInstance",
+            resultType = obj.defaultType,
+            jsCode = buildString {
+                append("() => ")
+                appendExternalClassReference(obj)
+            }
+        )
+    }
+
+    fun generateInstanceCheckForExternalClass(klass: IrClass) {
+        context.mapping.wasmExternalClassToInstanceCheck[klass] = createExternalJsFunction(
+            klass.name,
+            "_\$external_class_instanceof",
+            resultType = context.irBuiltIns.booleanType,
+            jsCode = buildString {
+                append("(x) => x instanceof ")
+                appendExternalClassReference(klass)
+            }
+        ).also {
+            it.addValueParameter("x", context.irBuiltIns.anyType)
+        }
+    }
+
+    private fun createExternalJsFunction(
+        originalName: Name,
+        suffix: String,
+        resultType: IrType,
+        jsCode: String,
+    ): IrSimpleFunction {
+        val res = context.irFactory.buildFun {
+            name = Name.identifier(originalName.asStringStripSpecialMarkers() + suffix)
+            returnType = resultType
+            isExternal = true
+        }
+        val builder = context.createIrBuilder(res.symbol)
+        res.annotations += builder.irCallConstructor(context.wasmSymbols.jsFunConstructor, typeArguments = emptyList()).also {
+            it.putValueArgument(0, builder.irString(jsCode))
+        }
+        res.parent = currentFile
+        addedDeclarations += res
+        return res
+    }
+}
+
+/**
+ * Redirect usages of complex declarations to top-level functions
+ */
+class ComplexExternalDeclarationsUsageLowering(val context: WasmBackendContext) : BodyLoweringPass {
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        irBody.transformChildrenVoid(object : IrElementTransformerVoid() {
+            override fun visitCall(expression: IrCall): IrExpression {
+                expression.transformChildrenVoid()
+                return transformCall(expression)
+            }
+
+            override fun visitConstructorCall(expression: IrConstructorCall): IrExpression {
+                expression.transformChildrenVoid()
+                return transformCall(expression)
+            }
+
+            override fun visitGetObjectValue(expression: IrGetObjectValue): IrExpression {
+                val externalGetInstance = context.mapping.wasmExternalObjectToGetInstanceFunction[expression.symbol.owner]
+                return if (externalGetInstance != null) {
+                    IrCallImpl(
+                        expression.startOffset,
+                        expression.endOffset,
+                        expression.type,
+                        externalGetInstance.symbol,
+                        valueArgumentsCount = 0,
+                        typeArgumentsCount = 0
+                    )
+                } else {
+                    expression
+                }
+            }
+
+            fun transformCall(call: IrFunctionAccessExpression): IrExpression {
+                val newFun: IrSimpleFunction? =
+                    context.mapping.wasmNestedExternalToNewTopLevelFunction[call.symbol.owner.realOverrideTarget]
+
+                return if (newFun != null) {
+                    irCall(call, newFun, receiversAsArguments = true)
+                } else {
+                    call
+                }
+            }
+        })
+    }
+}
+
+
diff --git a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/JsInteropFunctionsLowering.kt b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/JsInteropFunctionsLowering.kt
index c0a81cd5ffe..42eb5f57233 100644
--- a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/JsInteropFunctionsLowering.kt
+++ b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/JsInteropFunctionsLowering.kt
@@ -20,7 +20,10 @@ import org.jetbrains.kotlin.ir.backend.js.utils.getJsNameOrKotlinName
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.builders.declarations.*
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.IrBody
+import org.jetbrains.kotlin.ir.expressions.IrCall
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.IrStatementOriginImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrInstanceInitializerCallImpl
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
@@ -53,6 +56,8 @@ class JsInteropFunctionsLowering(val context: WasmBackendContext) : DeclarationT
         if (declaration !is IrSimpleFunction) return null
         val isExported = declaration.isExported()
         val isExternal = declaration.isExternal
+        if (declaration.isPropertyAccessor) return null
+        if (declaration.parent !is IrPackageFragment) return null
         if (!isExported && !isExternal) return null
         check(!(isExported && isExternal)) { "Exported external declarations are not supported: ${declaration.fqNameWhenAvailable}" }
         check(declaration.parent !is IrClass) { "Interop members are not supported:  ${declaration.fqNameWhenAvailable}" }
@@ -595,7 +600,7 @@ class JsInteropFunctionsLowering(val context: WasmBackendContext) : DeclarationT
     }
 }
 
-private fun StringBuilder.appendParameterList(size: Int) =
+internal fun StringBuilder.appendParameterList(size: Int) =
     repeat(size) {
         append("p")
         append(it)
diff --git a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmTypeOperatorLowering.kt b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmTypeOperatorLowering.kt
index 456ac17fec1..77ea6310319 100644
--- a/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmTypeOperatorLowering.kt
+++ b/compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmTypeOperatorLowering.kt
@@ -15,6 +15,7 @@ import org.jetbrains.kotlin.backend.common.lower.irNot
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.erasedUpperBound
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.getRuntimeClass
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.IrClass
@@ -151,9 +152,14 @@ class WasmBaseTypeOperatorTransformer(val context: WasmBackendContext) : IrEleme
 
     private fun generateTypeCheckNonNull(argument: IrExpression, toType: IrType): IrExpression {
         assert(!toType.isMarkedNullable())
+        val classOrInterface = toType.eraseToClassOrInterface
         return when {
-            // TODO: Use instanceof for classes later
-            toType.eraseToClassOrInterface.isExternal -> builder.irTrue()
+            classOrInterface.isExternal -> {
+                if (classOrInterface.kind == ClassKind.INTERFACE)
+                    builder.irTrue()
+                else
+                    generateIsExternalClass(argument, classOrInterface)
+            }
             toType.isNothing() -> builder.irFalse()
             toType.isTypeParameter() -> generateTypeCheckWithTypeParameter(argument, toType)
             toType.isInterface() -> generateIsInterface(argument, toType)
@@ -315,4 +321,11 @@ class WasmBaseTypeOperatorTransformer(val context: WasmBackendContext) : IrEleme
             putTypeArgument(0, toType)
         }
     }
+
+    private fun generateIsExternalClass(argument: IrExpression, klass: IrClass): IrExpression {
+        val function = context.mapping.wasmJsInteropFunctionToWrapper[context.mapping.wasmExternalClassToInstanceCheck[klass]!!]!!
+        return builder.irCall(function).also {
+            it.putValueArgument(0, argument)
+        }
+    }
 }
diff --git a/compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/JsMapping.kt b/compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/JsMapping.kt
index 2da271c9469..7ff4572d141 100644
--- a/compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/JsMapping.kt
+++ b/compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/JsMapping.kt
@@ -45,6 +45,15 @@ class JsMapping(val state: JsMappingState) : DefaultMapping(state) {
     // Wasm mappings
     val wasmJsInteropFunctionToWrapper =
         state.newDeclarationToDeclarationMapping<IrSimpleFunction, IrSimpleFunction>()
+
+    val wasmNestedExternalToNewTopLevelFunction =
+        state.newDeclarationToDeclarationMapping<IrFunction, IrSimpleFunction>()
+
+    val wasmExternalObjectToGetInstanceFunction =
+        state.newDeclarationToDeclarationMapping<IrClass, IrSimpleFunction>()
+
+    val wasmExternalClassToInstanceCheck =
+        state.newDeclarationToDeclarationMapping<IrClass, IrSimpleFunction>()
 }
 
 
diff --git a/compiler/testData/codegen/boxWasmJsInterop/externals.kt b/compiler/testData/codegen/boxWasmJsInterop/externals.kt
index 47f1751f731..318153a5246 100644
--- a/compiler/testData/codegen/boxWasmJsInterop/externals.kt
+++ b/compiler/testData/codegen/boxWasmJsInterop/externals.kt
@@ -1,6 +1,9 @@
 // FILE: externals.js
 function createObject() {
-    return {};
+    return {
+        getXmethod() { return this.x; },
+        setXmethod(v) { this.x = v; }
+    };
 }
 
 function setX(obj, x) {
@@ -11,15 +14,156 @@ function getX(obj) {
     return obj.x;
 }
 
+const readOnlyProp = 123;
+var mutableProp = "20";
+
+class C1 {
+    constructor(a, b) {
+        this.a = a;
+        this.b = b;
+    }
+
+    getA() { return this.a; }
+    setA(v) { this.a = v; }
+
+    getB() { return this.b; }
+}
+
+C1.Nested1 = class {}
+C1.Nested1.Nested2 = class {}
+C1.Nested1.Nested2.Nested3 = class {
+    constructor(x) {
+        this.x = x;
+    }
+
+    foo() { return this.x + " from Nested 3"; }
+}
+
+class C2 extends C1 {
+    constructor(a, b) {
+        super(a, b);
+        this.c = "C";
+    }
+}
+
+
+C2.Object1 = { Object2: { Object3: { x: "C2.Object1.Object2.Object3.x" } } }
+
+const externalObj = {
+    x: "externalObj.x",
+    y: {  x: "externalObj.y.x" },
+    c: class { x = "(new externalObj.c()).x" }
+}
+
+
 // FILE: externals.kt
-external interface Obj
+external interface Obj {
+    var x: Int
+    fun getXmethod(): Int
+    fun setXmethod(v: Int)
+}
 external fun createObject(): Obj
 external fun setX(obj: Obj, x: Int)
 external fun getX(obj: Obj): Int
 
+external val readOnlyProp: Int
+external var mutableProp: String
+
+open external class C1 {
+    constructor(a: String, b: String)
+    var a: String
+    val b: String
+
+    fun getA(): String
+    fun setA(x: String)
+    fun getB(): String
+
+    class Nested1 {
+        class Nested2 {
+            class Nested3 {
+                constructor(x: String)
+                fun foo(): String
+            }
+        }
+    }
+}
+
+external class C2 : C1 {
+    constructor(a: String, b: String)
+
+    val c: String
+
+    object Object1 {
+        object Object2 {
+            object Object3 {
+                val x: String
+            }
+        }
+    }
+}
+
+external object externalObj {
+    val x: String
+    object y {
+        val x: String
+    }
+    class c {
+        val x: String
+    }
+}
+
 fun box(): String {
     val obj = createObject()
     setX(obj, 100)
     if (getX(obj) != 100) return "Fail 2"
+
+    if (obj.x != 100) return "Fail 2.1"
+    obj.x = 200
+    if (getX(obj) != 200) return "Fail 2.2"
+    val objXRef = obj::x
+    objXRef.set(300)
+    if (getX(obj) != 300 || obj.x != 300 || objXRef.get() != 300) return "Fail 2.3"
+
+    if (obj.getXmethod() != 300) return "Fail 2.4"
+    obj.setXmethod(400)
+    if (obj.getXmethod() != 400 || getX(obj) != 400) return "Fail 2.5"
+
+    if (readOnlyProp != 123) return "Fail 3"
+    if (::readOnlyProp.get() != 123) return "Fail 4"
+    if (mutableProp != "20") return "Fail 5"
+    mutableProp = "30"
+    if (mutableProp != "30") return "Fail 6"
+    (::mutableProp).set("40")
+    if (mutableProp != "40") return "Fail 7"
+
+    val c1 = C1("A", "B")
+    if (c1.a != "A" || c1.b != "B") return "Fail 8"
+    if (c1.getA() != "A" || c1.getB() != "B") return "Fail 9"
+    c1.setA("A2")
+    if (c1.a != "A2") return "Fail 10"
+    c1.a = "A3"
+    if (c1.getA() != "A3") return "Fail 11"
+    val c2 = C2("A", "B")
+    if (c2.a != "A" || c2.b != "B" || c2.c != "C") return "Fail 12"
+    val c2_as_c1: C1 = c2
+    if (c2_as_c1.a != "A" || c2_as_c1.b != "B") return "Fail 13"
+
+    val nested3 = C1.Nested1.Nested2.Nested3("example")
+    if (nested3.foo() != "example from Nested 3") return "Fail 14"
+
+    if (C2.Object1.Object2.Object3.x != "C2.Object1.Object2.Object3.x") return "Fail 15"
+    if (externalObj.x != "externalObj.x") return "Fail 16"
+    if (externalObj.y.x != "externalObj.y.x") return "Fail 17"
+    if (externalObj.c().x != "(new externalObj.c()).x") return "Fail 18"
+
+
+    if (c1 as Any !is C1) return "Fail 19"
+    if (c2 as Any !is C1) return "Fail 20"
+    if (c2 as Any !is C2) return "Fail 21"
+    if (externalObj.c() as Any !is externalObj.c) return "Fail 22"
+    if (10 as Any is C1) return "Fail 23"
+    if (c1 as Any is C2) return "Fail 24"
+
+
     return "OK"
 }
\ No newline at end of file