diff --git a/src/observable/list/BaseMappedList.ts b/src/observable/list/BaseMappedList.ts
index 0435a760..8646153e 100644
--- a/src/observable/list/BaseMappedList.ts
+++ b/src/observable/list/BaseMappedList.ts
@@ -45,8 +45,7 @@ export class BaseMappedList<F,T,R = T> extends BaseObservableList<T> {
         return this._mappedValues!.length;
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): IterableIterator<T> {
         return this._mappedValues!.values();
     }
 }
diff --git a/src/observable/list/ConcatList.ts b/src/observable/list/ConcatList.ts
index aaad5a6a..80accb81 100644
--- a/src/observable/list/ConcatList.ts
+++ b/src/observable/list/ConcatList.ts
@@ -86,13 +86,11 @@ export class ConcatList<T> extends BaseObservableList<T> implements IListObserve
         return len;
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): Iterator<T> {
         let sourceListIdx = 0;
         let it = this._sourceLists[0][Symbol.iterator]();
         return {
-            // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-            next: () => {
+            next: (): IteratorResult<T> => {
                 let result = it.next();
                 while (result.done) {
                     sourceListIdx += 1;
diff --git a/src/observable/list/ObservableArray.ts b/src/observable/list/ObservableArray.ts
index 662f715e..1b962e81 100644
--- a/src/observable/list/ObservableArray.ts
+++ b/src/observable/list/ObservableArray.ts
@@ -75,8 +75,7 @@ export class ObservableArray<T> extends BaseObservableList<T> {
         return this._items.length;
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): IterableIterator<T> {
         return this._items.values();
     }
 }
diff --git a/src/observable/list/SortedArray.ts b/src/observable/list/SortedArray.ts
index c956f7b8..e4723db1 100644
--- a/src/observable/list/SortedArray.ts
+++ b/src/observable/list/SortedArray.ts
@@ -112,40 +112,31 @@ export class SortedArray<T> extends BaseObservableList<T> {
         return this._items.length;
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): Iterator<T> {
         return new Iterator(this);
     }
 }
 
 // iterator that works even if the current value is removed while iterating
 class Iterator<T> {
-    private _sortedArray: SortedArray<T> | null
-    private _current: T | null | undefined
+    private _sortedArray: SortedArray<T>;
+    private _current: T | null | undefined;
+    private _consumed: boolean = false;
 
     constructor(sortedArray: SortedArray<T>) {
         this._sortedArray = sortedArray;
         this._current = null;
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    next() {
-        if (this._sortedArray) {
-            if (this._current) {
-                this._current = this._sortedArray._getNext(this._current);
-            } else {
-                this._current = this._sortedArray.get(0);
-            }
-            if (this._current) {
-                return {value: this._current};
-            } else {
-                // cause done below
-                this._sortedArray = null;
-            }
+    next(): IteratorResult<T> {
+        if (this._consumed) {
+            return {value: undefined, done: true};
         }
-        if (!this._sortedArray) {
-            return {done: true};
+        this._current = this._current? this._sortedArray._getNext(this._current): this._sortedArray.get(0);
+        if (!this._current) {
+            this._consumed = true;
         }
+        return { value: this._current, done: this._consumed } as IteratorResult<T>;
     }
 }
 
diff --git a/src/observable/map/ApplyMap.ts b/src/observable/map/ApplyMap.ts
index a13cf757..0c4962c8 100644
--- a/src/observable/map/ApplyMap.ts
+++ b/src/observable/map/ApplyMap.ts
@@ -79,7 +79,9 @@ export class ApplyMap<K, V> extends BaseObservableMap<K, V> {
 
     onUnsubscribeLast(): void {
         super.onUnsubscribeLast();
-        if (this._subscription) this._subscription = this._subscription();
+        if (this._subscription) {
+            this._subscription = this._subscription();
+        }
     }
 
     onReset(): void {
@@ -89,8 +91,7 @@ export class ApplyMap<K, V> extends BaseObservableMap<K, V> {
         this.emitReset();
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): Iterator<[K, V]> {
         return this._source[Symbol.iterator]();
     }
 
diff --git a/src/observable/map/FilteredMap.ts b/src/observable/map/FilteredMap.ts
index 1fd7d89a..c97bc48a 100644
--- a/src/observable/map/FilteredMap.ts
+++ b/src/observable/map/FilteredMap.ts
@@ -142,8 +142,7 @@ export class FilteredMap<K, V> extends BaseObservableMap<K, V> {
         this.emitReset();
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): FilterIterator<K, V> {
         return new FilterIterator<K, V>(this._source, this._included);
     }
 
@@ -157,7 +156,7 @@ export class FilteredMap<K, V> extends BaseObservableMap<K, V> {
         return count;
     }
 
-    get(key): V | undefined{
+    get(key: K): V | undefined {
         const value = this._source.get(key);
         if (value && this._filter(value, key)) {
             return value;
@@ -173,8 +172,7 @@ class FilterIterator<K, V> {
         this._sourceIterator = map[Symbol.iterator]();
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    next() {
+    next(): IteratorResult<[K, V]> {
         // eslint-disable-next-line no-constant-condition
         while (true) {
             const sourceResult = this._sourceIterator.next();
diff --git a/src/observable/map/LogMap.ts b/src/observable/map/LogMap.ts
index 60ac7721..ce9d343e 100644
--- a/src/observable/map/LogMap.ts
+++ b/src/observable/map/LogMap.ts
@@ -72,8 +72,7 @@ export class LogMap<K, V> extends BaseObservableMap<K, V> {
         this.emitReset();
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): Iterator<[K, V]> {
         return this._source[Symbol.iterator]();
     }
 
diff --git a/src/observable/map/MappedMap.ts b/src/observable/map/MappedMap.ts
index 0d2c47c0..6ada079f 100644
--- a/src/observable/map/MappedMap.ts
+++ b/src/observable/map/MappedMap.ts
@@ -64,7 +64,9 @@ export class MappedMap<K, V, MappedV> extends BaseObservableMap<K, MappedV> {
     onRemove(key: K/*, _value*/): void {
         const mappedValue = this._mappedValues.get(key);
         if (this._mappedValues.delete(key)) {
-            if (mappedValue) this.emitRemove(key, mappedValue);
+            if (mappedValue) {
+                this.emitRemove(key, mappedValue);
+            }
         }
     }
 
@@ -93,7 +95,9 @@ export class MappedMap<K, V, MappedV> extends BaseObservableMap<K, MappedV> {
 
     onUnsubscribeLast(): void {
         super.onUnsubscribeLast();
-        if (this._subscription) this._subscription = this._subscription();
+        if (this._subscription) {
+            this._subscription = this._subscription();
+        }
         this._mappedValues.clear();
     }
 
@@ -102,8 +106,7 @@ export class MappedMap<K, V, MappedV> extends BaseObservableMap<K, MappedV> {
         this.emitReset();
     }
 
-    // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-    [Symbol.iterator]() {
+    [Symbol.iterator](): IterableIterator<[K, MappedV]> {
         return this._mappedValues.entries();
     }
 
diff --git a/src/observable/map/ObservableMap.ts b/src/observable/map/ObservableMap.ts
index c5ffe397..f0d4c77a 100644
--- a/src/observable/map/ObservableMap.ts
+++ b/src/observable/map/ObservableMap.ts
@@ -97,7 +97,7 @@ export class ObservableMap<K, V> extends BaseObservableMap<K, V> {
     keys(): Iterator<K> {
         return this._values.keys();
     }
-};
+}
 
 // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
 export function tests() {