diff --git a/scripts/generateDocs.ts b/scripts/generateDocs.ts
index 694c4feec..d9a2ff247 100644
--- a/scripts/generateDocs.ts
+++ b/scripts/generateDocs.ts
@@ -22,7 +22,6 @@ import ThemeViewState from "../src/Models/ThemeViewState"
 import Validators from "../src/UI/InputElement/Validators"
 import questions from "../public/assets/generated/layers/questions.json"
 import { LayerConfigJson } from "../src/Models/ThemeConfig/Json/LayerConfigJson"
-import { Utils } from "../src/Utils"
 import { TagUtils } from "../src/Logic/Tags/TagUtils"
 import Script from "./Script"
 import { Changes } from "../src/Logic/Osm/Changes"
@@ -562,7 +561,7 @@ export class GenerateDocs extends Script {
                         item.url.startsWith("pmtiles://")
                 )
         )
-        const serverInfos = Utils.DedupOnId(serverInfosDupl, (item) => item.url)
+        const serverInfos = Lists.dedupOnId(serverInfosDupl, (item) => item.url)
         const titles = Lists.dedup(Lists.noEmpty(serverInfos.map((s) => s.category)))
         titles.sort()
 
diff --git a/scripts/generateLicenseInfo.ts b/scripts/generateLicenseInfo.ts
index 2cb5ee215..a1352a612 100644
--- a/scripts/generateLicenseInfo.ts
+++ b/scripts/generateLicenseInfo.ts
@@ -327,7 +327,7 @@ export class GenerateLicenseInfo extends Script {
             }
 
             licenses.sort((a, b) => (a.path < b.path ? -1 : 1))
-            licenses = Utils.DedupOnId(licenses, (l) => l.path)
+            licenses = Lists.dedupOnId(licenses, (l) => l.path)
             const path = dir + "/license_info.json"
             if (licenses.length === 0) {
                 console.log("Removing", path, "as it is empty")
diff --git a/src/Logic/ImageProviders/AllImageProviders.ts b/src/Logic/ImageProviders/AllImageProviders.ts
index d4caf5b34..bff020e47 100644
--- a/src/Logic/ImageProviders/AllImageProviders.ts
+++ b/src/Logic/ImageProviders/AllImageProviders.ts
@@ -6,7 +6,6 @@ import { ImmutableStore, Store, Stores } from "../UIEventSource"
 import ImageProvider, { ProvidedImage } from "./ImageProvider"
 import { WikidataImageProvider } from "./WikidataImageProvider"
 import Panoramax from "./Panoramax"
-import { Utils } from "../../Utils"
 import { ServerSourceInfo } from "../../Models/SourceOverview"
 import { Lists } from "../../Utils/Lists"
 
@@ -151,7 +150,7 @@ export default class AllImageProviders {
         }
         const source = Stores.concat(allSources).map((result) => {
             const all = result.flatMap((x) => x)
-            return Utils.DedupOnId(all, (i) => [i?.id, i?.url, i?.alt_id])
+            return Lists.dedupOnId(all, (i) => [i?.id, i?.url, i?.alt_id])
         })
         this._cachedImageStores[cachekey] = source
         return source
diff --git a/src/Logic/Web/NearbyImagesSearch.ts b/src/Logic/Web/NearbyImagesSearch.ts
index 576d012fb..75ea0f9f0 100644
--- a/src/Logic/Web/NearbyImagesSearch.ts
+++ b/src/Logic/Web/NearbyImagesSearch.ts
@@ -10,6 +10,7 @@ import { Point } from "geojson"
 import { ImageData, Panoramax, PanoramaxXYZ } from "panoramax-js/dist"
 import { Mapillary } from "../ImageProviders/Mapillary"
 import { ServerSourceInfo } from "../../Models/SourceOverview"
+import { Lists } from "../../Utils/Lists"
 
 interface ImageFetcher {
     /**
@@ -465,6 +466,6 @@ export class CombinedFetcher {
             this.fetchImage(source, lat, lon, state, sink)
         }
 
-        return { images: sink.mapD((imgs) => Utils.DedupOnId(imgs, (i) => i["id"])), state }
+        return { images: sink.mapD((imgs) => Lists.dedupOnId(imgs, (i) => i["id"])), state }
     }
 }
diff --git a/src/Models/SourceOverview.ts b/src/Models/SourceOverview.ts
index 5d4cf5e66..63d7a4606 100644
--- a/src/Models/SourceOverview.ts
+++ b/src/Models/SourceOverview.ts
@@ -10,7 +10,9 @@ import ThemeConfig from "../../src/Models/ThemeConfig/ThemeConfig"
 import { ThemeConfigJson } from "../../src/Models/ThemeConfig/Json/ThemeConfigJson"
 import SpecialVisualizations from "../../src/UI/SpecialVisualizations"
 import ValidationUtils from "../../src/Models/ThemeConfig/Conversion/ValidationUtils"
-import { QuestionableTagRenderingConfigJson } from "../../src/Models/ThemeConfig/Json/QuestionableTagRenderingConfigJson"
+import {
+    QuestionableTagRenderingConfigJson
+} from "../../src/Models/ThemeConfig/Json/QuestionableTagRenderingConfigJson"
 import { LayerConfigJson } from "../../src/Models/ThemeConfig/Json/LayerConfigJson"
 import { Lists } from "../Utils/Lists"
 
@@ -206,7 +208,7 @@ export class SourceOverview {
         }
         urls = urls.filter((item) => !!item?.url)
         urls.sort((a, b) => (a < b ? -1 : 1))
-        urls = Utils.DedupOnId(urls, (item) => item.url)
+        urls = Lists.dedupOnId(urls, (item) => item.url)
         this.eliUrlsCached = urls
         return urls
     }
diff --git a/src/Models/ThemeConfig/Conversion/PrepareLayer.ts b/src/Models/ThemeConfig/Conversion/PrepareLayer.ts
index 11b849c3c..6db428e67 100644
--- a/src/Models/ThemeConfig/Conversion/PrepareLayer.ts
+++ b/src/Models/ThemeConfig/Conversion/PrepareLayer.ts
@@ -1,18 +1,6 @@
-import {
-    Concat,
-    DesugaringContext,
-    DesugaringStep,
-    Each,
-    FirstOf,
-    Fuse,
-    On,
-    SetDefault,
-} from "./Conversion"
+import { Concat, DesugaringContext, DesugaringStep, Each, FirstOf, Fuse, On, SetDefault } from "./Conversion"
 import { LayerConfigJson } from "../Json/LayerConfigJson"
-import {
-    MinimalTagRenderingConfigJson,
-    TagRenderingConfigJson,
-} from "../Json/TagRenderingConfigJson"
+import { MinimalTagRenderingConfigJson, TagRenderingConfigJson } from "../Json/TagRenderingConfigJson"
 import { Utils } from "../../../Utils"
 import RewritableConfigJson from "../Json/RewritableConfigJson"
 import SpecialVisualizations from "../../../UI/SpecialVisualizations"
@@ -1163,7 +1151,9 @@ export class PrepareLayer extends Fuse<LayerConfigJson> {
             "Fully prepares and expands a layer for the LayerConfig.",
             new DeriveSource(),
             new On("tagRenderings", new Each(new RewriteSpecial())),
-            new On("tagRenderings", new Concat(new ExpandRewrite()).andThenF(Utils.Flatten)),
+            new On("tagRenderings", new Concat(new ExpandRewrite()).andThenF(function <T>(list: (T | T[])[]): T[] {
+              return Lists.flatten(list)
+            })),
             new On(
                 "tagRenderings",
                 (layer) =>
@@ -1180,7 +1170,9 @@ export class PrepareLayer extends Fuse<LayerConfigJson> {
             new On<
                 (LineRenderingConfigJson | RewritableConfigJson<LineRenderingConfigJson>)[],
                 LayerConfigJson
-            >("lineRendering", new Each(new ExpandRewrite()).andThenF(Utils.Flatten)),
+            >("lineRendering", new Each(new ExpandRewrite()).andThenF(function <T>(list: (T | T[])[]): T[] {
+              return Lists.flatten(list)
+            })),
             new On<PointRenderingConfigJson[], LayerConfigJson>(
                 "pointRendering",
                 (layer) =>
diff --git a/src/Models/ThemeConfig/Conversion/PrevalidateLayer.ts b/src/Models/ThemeConfig/Conversion/PrevalidateLayer.ts
index 55918223e..1f73474fc 100644
--- a/src/Models/ThemeConfig/Conversion/PrevalidateLayer.ts
+++ b/src/Models/ThemeConfig/Conversion/PrevalidateLayer.ts
@@ -178,9 +178,7 @@ export class PrevalidateLayer extends DesugaringStep<LayerConfigJson> {
 
             {
                 // Check for multiple, identical builtin questions - usability for studio users
-                const duplicates = Utils.Duplicates(
-                    <string[]>json.tagRenderings.filter((tr) => typeof tr === "string")
-                )
+                const duplicates = Lists.duplicates(<string[]>json.tagRenderings.filter((tr) => typeof tr === "string"))
                 for (let i = 0; i < json.tagRenderings.length; i++) {
                     const tagRendering = json.tagRenderings[i]
                     if (typeof tagRendering === "string" && duplicates.indexOf(tagRendering) > 0) {
@@ -209,7 +207,7 @@ export class PrevalidateLayer extends DesugaringStep<LayerConfigJson> {
         {
             // duplicate ids in tagrenderings check
             const duplicates = Lists.noNull(
-                Utils.Duplicates(json.tagRenderings?.map((tr) => tr?.["id"]))
+                Lists.duplicates(json.tagRenderings?.map((tr) => tr?.["id"]))
             )
             if (duplicates?.length > 0) {
                 // It is tempting to add an index to this warning; however, due to labels the indices here might be different from the index in the tagRendering list
@@ -312,9 +310,7 @@ export class PrevalidateLayer extends DesugaringStep<LayerConfigJson> {
                     )
             }
 
-            const duplicateIds = Utils.Duplicates(
-                (json.tagRenderings ?? [])?.map((f) => f["id"]).filter((id) => id !== "questions")
-            )
+            const duplicateIds = Lists.duplicates((json.tagRenderings ?? [])?.map((f) => f["id"]).filter((id) => id !== "questions"))
             if (duplicateIds.length > 0 && !Utils.runningFromConsole) {
                 context
                     .enter("tagRenderings")
diff --git a/src/Models/ThemeConfig/Conversion/ValidateTheme.ts b/src/Models/ThemeConfig/Conversion/ValidateTheme.ts
index e24ce8c46..25d2fbf22 100644
--- a/src/Models/ThemeConfig/Conversion/ValidateTheme.ts
+++ b/src/Models/ThemeConfig/Conversion/ValidateTheme.ts
@@ -7,6 +7,7 @@ import ThemeConfig from "../ThemeConfig"
 import { Utils } from "../../../Utils"
 import { DetectDuplicatePresets, DoesImageExist, ValidateLanguageCompleteness } from "./Validation"
 import Constants from "../../Constants"
+import { Lists } from "../../../Utils/Lists"
 
 export class ValidateTheme extends DesugaringStep<ThemeConfigJson> {
     /**
@@ -105,7 +106,7 @@ export class ValidateTheme extends DesugaringStep<ThemeConfigJson> {
                 }
                 this._validateImage.convert(theme.icon, context.enter("icon"))
             }
-            const dups = Utils.Duplicates(json.layers.map((layer) => layer["id"]))
+            const dups = Lists.duplicates(json.layers.map((layer) => layer["id"]))
             if (dups.length > 0) {
                 context.err(
                     `The theme ${json.id} defines multiple layers with id ${dups.join(", ")}`
diff --git a/src/Models/ThemeConfig/Conversion/Validation.ts b/src/Models/ThemeConfig/Conversion/Validation.ts
index 2b87c97b6..4d4919442 100644
--- a/src/Models/ThemeConfig/Conversion/Validation.ts
+++ b/src/Models/ThemeConfig/Conversion/Validation.ts
@@ -24,6 +24,7 @@ import { AvailableRasterLayers } from "../../RasterLayers"
 import { eliCategory } from "../../RasterLayerProperties"
 import licenses from "../../../assets/generated/license_info.json"
 import { Strings } from "../../../Utils/Strings"
+import { Lists } from "../../../Utils/Lists"
 
 export class ValidateLanguageCompleteness extends DesugaringStep<ThemeConfig> {
     private readonly _languages: string[]
@@ -1064,7 +1065,7 @@ export class DetectDuplicatePresets extends DesugaringStep<ThemeConfig> {
 
         const enNames = presets.map((p) => p.title.textFor("en"))
         if (new Set(enNames).size != enNames.length) {
-            const dups = Utils.Duplicates(enNames)
+            const dups = Lists.duplicates(enNames)
             const layersWithDup = json.layers.filter((l) =>
                 l.presets.some((p) => dups.indexOf(p.title.textFor("en")) >= 0)
             )
diff --git a/src/Models/ThemeConfig/LayerConfig.ts b/src/Models/ThemeConfig/LayerConfig.ts
index 3fa07c22f..8ca0de4e2 100644
--- a/src/Models/ThemeConfig/LayerConfig.ts
+++ b/src/Models/ThemeConfig/LayerConfig.ts
@@ -13,7 +13,6 @@ import PointRenderingConfig from "./PointRenderingConfig"
 import WithContextLoader from "./WithContextLoader"
 import LineRenderingConfig from "./LineRenderingConfig"
 import { TagRenderingConfigJson } from "./Json/TagRenderingConfigJson"
-import { Utils } from "../../Utils"
 import { TagsFilter } from "../../Logic/Tags/TagsFilter"
 import FilterConfigJson from "./Json/FilterConfigJson"
 import { Overpass } from "../../Logic/Osm/Overpass"
@@ -340,7 +339,7 @@ export default class LayerConfig extends WithContextLoader {
         }
 
         {
-            const duplicateIds = Utils.Duplicates(this.filters.map((f) => f.id))
+            const duplicateIds = Lists.duplicates(this.filters.map((f) => f.id))
             if (duplicateIds.length > 0) {
                 throw `Some filters have a duplicate id: ${duplicateIds} (at ${context}.filters)`
             }
diff --git a/src/UI/BigComponents/OfflineManagement.svelte b/src/UI/BigComponents/OfflineManagement.svelte
index 21dc74914..7d37a3e6c 100644
--- a/src/UI/BigComponents/OfflineManagement.svelte
+++ b/src/UI/BigComponents/OfflineManagement.svelte
@@ -23,6 +23,7 @@
   import Translations from "../i18n/Translations"
   import { default as Trans } from "../Base/Tr.svelte"
   import AccordionSingle from "../Flowbite/AccordionSingle.svelte"
+  import { Lists } from "../../Utils/Lists"
 
   export let state: ThemeViewState & SpecialVisualizationState = undefined
   export let autoDownload = state.autoDownloadOfflineBasemap
@@ -202,7 +203,7 @@
         <AccordionItem paddingDefault="p-2">
           <Trans t={t.overview} slot="header" />
           <div class="leave-room">
-            {Utils.toHumanByteSize(Utils.sum($installed.map((area) => area.size)))}
+            {Utils.toHumanByteSize(Lists.sum($installed.map((area) => area.size)))}
             <button
               on:click={() => {
                 installed?.data?.forEach((area) => del(area))
diff --git a/src/UI/BigComponents/ThemesList.svelte b/src/UI/BigComponents/ThemesList.svelte
index 8684a9cb4..90b0ed211 100644
--- a/src/UI/BigComponents/ThemesList.svelte
+++ b/src/UI/BigComponents/ThemesList.svelte
@@ -8,6 +8,7 @@
   import Translations from "../i18n/Translations"
   import Tr from "../Base/Tr.svelte"
   import { Utils } from "../../Utils"
+  import { Lists } from "../../Utils/Lists"
 
   export let search: UIEventSource<string> = new UIEventSource<string>(undefined)
   export let themes: MinimalThemeInformation[]
@@ -23,7 +24,7 @@
       ? "flex flex-wrap items-center justify-center gap-x-2"
       : "theme-list my-2 gap-4 md:grid md:grid-flow-row md:grid-cols-2 lg:grid-cols-3"}
   >
-    {#each Utils.DedupOnId(Utils.noNull(themes)) as theme (theme.id)}
+    {#each Lists.dedupOnId(Utils.noNull(themes)) as theme (theme.id)}
       <ThemeButton {theme} {state} iconOnly={onlyIcons}>
         {#if $search && hasSelection && themes?.[0] === theme}
           <span class="thanks hidden-on-mobile" aria-hidden="true">
diff --git a/src/UI/OpeningHours/Visualisation/RegularOpeningHoursTable.svelte b/src/UI/OpeningHours/Visualisation/RegularOpeningHoursTable.svelte
index 6fcf9cac7..1baf7983b 100644
--- a/src/UI/OpeningHours/Visualisation/RegularOpeningHoursTable.svelte
+++ b/src/UI/OpeningHours/Visualisation/RegularOpeningHoursTable.svelte
@@ -9,10 +9,9 @@
   import OpeningHoursRangeElement from "./OpeningHoursRangeElement.svelte"
   import { Translation } from "../../i18n/Translation"
   import Translations from "../../i18n/Translations"
-  import { OH } from "../OpeningHours"
   import type { OpeningRange } from "../OpeningHours"
-
-  import { Utils } from "../../../Utils"
+  import { OH } from "../OpeningHours"
+  import { Lists } from "../../../Utils/Lists"
 
   export let oh: opening_hours
   export let ranges: OpeningRange[][] // Per weekday
@@ -47,7 +46,7 @@
     changeTexts: string[]
   }[] = OH.partitionOHForDistance(changeHoursWeekend, changeHourTextWeekend)
 
-  let allChangeMoments: number[] = Utils.DedupT([...changeHours, ...changeHoursWeekend])
+  let allChangeMoments: number[] = Lists.dedupT([...changeHours, ...changeHoursWeekend])
   let todayChangeMoments: Set<number> = new Set(OH.allChangeMoments(todayRanges)[0])
   // By default, we always show the range between 8 - 19h, in order to give a stable impression
   // Ofc, a bigger range is used if needed
diff --git a/src/UI/Studio/SchemaBasedArray.svelte b/src/UI/Studio/SchemaBasedArray.svelte
index 4c1e3ff36..806ece8eb 100644
--- a/src/UI/Studio/SchemaBasedArray.svelte
+++ b/src/UI/Studio/SchemaBasedArray.svelte
@@ -5,10 +5,12 @@
   import { TrashIcon } from "@babeard/svelte-heroicons/mini"
   import ShowConversionMessage from "./ShowConversionMessage.svelte"
   import Markdown from "../Base/Markdown.svelte"
-  import type { QuestionableTagRenderingConfigJson } from "../../Models/ThemeConfig/Json/QuestionableTagRenderingConfigJson"
+  import type {
+    QuestionableTagRenderingConfigJson
+  } from "../../Models/ThemeConfig/Json/QuestionableTagRenderingConfigJson"
   import CollapsedTagRenderingPreview from "./CollapsedTagRenderingPreview.svelte"
   import { Accordion } from "flowbite-svelte"
-  import { Utils } from "../../Utils"
+  import { Lists } from "../../Utils/Lists"
 
   export let state: EditJsonState<any>
   export let path: (string | number)[] = []
@@ -39,7 +41,7 @@
 
   let datapath = path
   const currentValue = state.getStoreFor<(string | QuestionableTagRenderingConfigJson)[]>(datapath)
-  currentValue.set(Utils.DedupT(currentValue.data))
+  currentValue.set(Lists.dedupT(currentValue.data))
   console.log("Current value is", currentValue.data)
   if (currentValue.data === undefined) {
     currentValue.setData([])
diff --git a/src/Utils.ts b/src/Utils.ts
index c7f54c30a..f240ed0f3 100644
--- a/src/Utils.ts
+++ b/src/Utils.ts
@@ -252,99 +252,6 @@ In the case that MapComplete is pointed to the testing grounds, the edit will be
         }
         return str
     }
-    public static DedupT<T>(arr: T[]): T[] {
-        if (!arr) {
-            return arr
-        }
-        const items = []
-        for (const item of arr) {
-            if (items.indexOf(item) < 0) {
-                items.push(item)
-            }
-        }
-        return items
-    }
-
-    /**
-     * Deduplicates the given array based on some ID-properties.
-     * Removes all falsey values
-     * @param arr
-     * @param toKey
-     * @constructor
-     */
-    public static DedupOnId<T = { id: string }>(
-        arr: T[],
-        toKey?: (t: T) => string | string[]
-    ): T[] {
-        const uniq: T[] = []
-        const seen = new Set<string>()
-        if (toKey === undefined) {
-            toKey = (item) => item["id"]
-        }
-        for (const img of arr) {
-            if (!img) {
-                continue
-            }
-            const ks = toKey(img)
-            if (typeof ks === "string") {
-                if (!seen.has(ks)) {
-                    seen.add(ks)
-                    uniq.push(img)
-                }
-            } else if (ks) {
-                const ksNoNull = Lists.noNull(ks)
-                const hasBeenSeen = ksNoNull.some((k) => seen.has(k))
-                if (!hasBeenSeen) {
-                    uniq.push(img)
-                }
-                for (const k of ksNoNull) {
-                    seen.add(k)
-                }
-            }
-        }
-        return uniq
-    }
-
-    /**
-     * Finds all duplicates in a list of strings
-     *
-     * Utils.Duplicates(["a", "b", "c"]) // => []
-     * Utils.Duplicates(["a", "b","c","b"] // => ["b"]
-     * Utils.Duplicates(["a", "b","c","b","b"] // => ["b"]
-     *
-     */
-    public static Duplicates(arr: string[]): string[] {
-        if (arr === undefined) {
-            return undefined
-        }
-        const seen = new Set<string>()
-        const duplicates = new Set<string>()
-        for (const string of arr) {
-            if (seen.has(string)) {
-                duplicates.add(string)
-            }
-            seen.add(string)
-        }
-        return Array.from(duplicates)
-    }
-
-    /**
-     * In the given list, all values which are lists will be merged with the values, e.g.
-     *
-     * Utils.Flatten([ [1,2], 3, [4, [5 ,6]] ]) // => [1, 2, 3, 4, [5, 6]]
-     */
-    public static Flatten<T>(list: (T | T[])[]): T[] {
-        const result = []
-        for (const value of list) {
-            if (Array.isArray(value)) {
-                result.push(...value)
-            } else {
-                result.push(value)
-            }
-        }
-        return result
-    }
-
     /**
      * Utils.Identical([1,2], [1,2]) // => true
      * Utils.Identical([1,2,3], [1,2,4}]) // => false
@@ -1787,14 +1694,6 @@ In the case that MapComplete is pointed to the testing grounds, the edit will be
         return href
     }
 
-    public static sum(list: number[]): number {
-        let total = 0
-        for (const number of list) {
-            total += number
-        }
-        return total
-    }
-
     /**
      *
      * JSON.stringify(Utils.reorder({b: "0", a: "1"}, ["a", "b"])) // => '{"a":"1","b":"0"}'
diff --git a/src/Utils/Lists.ts b/src/Utils/Lists.ts
index 7de4b693f..7340dbe68 100644
--- a/src/Utils/Lists.ts
+++ b/src/Utils/Lists.ts
@@ -86,4 +86,93 @@ export class Lists {
         }
         return items
     }
+
+    public static sum(list: number[]): number {
+        let total = 0
+        for (const number of list) {
+            total += number
+        }
+        return total
+    }
+
+    /**
+     * In the given list, all values which are lists will be merged with the values, e.g.
+     *
+     * Utils.Flatten([ [1,2], 3, [4, [5 ,6]] ]) // => [1, 2, 3, 4, [5, 6]]
+     */
+    public static flatten<T>(list: (T | T[])[]): T[] {
+        const result = []
+        for (const value of list) {
+            if (Array.isArray(value)) {
+                result.push(...value)
+            } else {
+                result.push(value)
+            }
+        }
+        return result
+    }
+
+    /**
+     * Deduplicates the given array based on some ID-properties.
+     * Removes all falsey values
+     * @param arr
+     * @param toKey
+     * @constructor
+     */
+    public static dedupOnId<T = { id: string }>(
+        arr: T[],
+        toKey?: (t: T) => string | string[]
+    ): T[] {
+        const uniq: T[] = []
+        const seen = new Set<string>()
+        if (toKey === undefined) {
+            toKey = (item) => item["id"]
+        }
+        for (const img of arr) {
+            if (!img) {
+                continue
+            }
+            const ks = toKey(img)
+            if (typeof ks === "string") {
+                if (!seen.has(ks)) {
+                    seen.add(ks)
+                    uniq.push(img)
+                }
+            } else if (ks) {
+                const ksNoNull = Lists.noNull(ks)
+                const hasBeenSeen = ksNoNull.some((k) => seen.has(k))
+                if (!hasBeenSeen) {
+                    uniq.push(img)
+                }
+                for (const k of ksNoNull) {
+                    seen.add(k)
+                }
+            }
+        }
+        return uniq
+    }
+
+    /**
+     * Finds all duplicates in a list of strings
+     *
+     * Utils.Duplicates(["a", "b", "c"]) // => []
+     * Utils.Duplicates(["a", "b","c","b"] // => ["b"]
+     * Utils.Duplicates(["a", "b","c","b","b"] // => ["b"]
+     *
+     */
+    public static duplicates(arr: string[]): string[] {
+        if (arr === undefined) {
+            return undefined
+        }
+        const seen = new Set<string>()
+        const duplicates = new Set<string>()
+        for (const string of arr) {
+            if (seen.has(string)) {
+                duplicates.add(string)
+            }
+            seen.add(string)
+        }
+        return Array.from(duplicates)
+    }
+
 }