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feat: support TS syntax in no-magic-numbers (#19561)
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4 files changed

+1314
-67
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4 files changed

+1314
-67
lines changed

‎docs/src/rules/no-magic-numbers.md‎

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Original file line numberDiff line numberDiff line change
@@ -128,6 +128,7 @@ data[100] = a;
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f(data[0]);
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a = data[-0]; // same as data[0], -0 will be coerced to "0"
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a = data[+1]; // same as data[1], +1 will be coerced to "1"
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a = data[0xAB];
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@@ -207,6 +208,7 @@ Examples of **correct** code for the `{ "ignoreClassFieldInitialValues": true }`
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class C {
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foo = 2;
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bar = -3;
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tux = +1;
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#baz = 4;
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static qux = 5;
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}
@@ -290,3 +292,131 @@ const dutyFreePrice = 100,
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```
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:::
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### ignoreEnums (TypeScript only)
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Whether enums used in TypeScript are considered okay. `false` by default.
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Examples of **incorrect** code for the `{ "ignoreEnums": false }` option:
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::: incorrect
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreEnums": false }]*/
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enum foo {
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SECOND = 1000,
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}
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```
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:::
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Examples of **correct** code for the `{ "ignoreEnums": true }` option:
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::: correct
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreEnums": true }]*/
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enum foo {
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SECOND = 1000,
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}
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```
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:::
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### ignoreNumericLiteralTypes (TypeScript only)
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Whether numbers used in TypeScript numeric literal types are considered okay. `false` by default.
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Examples of **incorrect** code for the `{ "ignoreNumericLiteralTypes": false }` option:
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::: incorrect
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreNumericLiteralTypes": false }]*/
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type Foo = 1 | 2 | 3;
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```
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:::
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Examples of **correct** code for the `{ "ignoreNumericLiteralTypes": true }` option:
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::: correct
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreNumericLiteralTypes": true }]*/
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type Foo = 1 | 2 | 3;
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```
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:::
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### ignoreReadonlyClassProperties (TypeScript only)
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Whether numbers used in TypeScript readonly class properties are considered okay. `false` by default.
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Examples of **incorrect** code for the `{ "ignoreReadonlyClassProperties": false }` option:
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::: incorrect
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreReadonlyClassProperties": false }]*/
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class Foo {
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readonly A = 1;
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readonly B = 2;
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public static readonly C = 1;
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static readonly D = 1;
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}
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```
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:::
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Examples of **correct** code for the `{ "ignoreReadonlyClassProperties": true }` option:
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::: correct
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreReadonlyClassProperties": true }]*/
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class Foo {
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readonly A = 1;
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readonly B = 2;
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public static readonly C = 1;
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static readonly D = 1;
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}
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```
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:::
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### ignoreTypeIndexes (TypeScript only)
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Whether numbers used to index types are okay. `false` by default.
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Examples of **incorrect** code for the `{ "ignoreTypeIndexes": false }` option:
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::: incorrect
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreTypeIndexes": false }]*/
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type Foo = Bar[0];
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type Baz = Parameters<Foo>[2];
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```
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:::
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Examples of **correct** code for the `{ "ignoreTypeIndexes": true }` option:
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::: correct
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```ts
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/*eslint no-magic-numbers: ["error", { "ignoreTypeIndexes": true }]*/
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type Foo = Bar[0];
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type Baz = Parameters<Foo>[2];
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```
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:::

‎lib/rules/no-magic-numbers.js‎

Lines changed: 98 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -26,10 +26,73 @@ function normalizeIgnoreValue(x) {
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return x;
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}
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/**
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* Checks if the node parent is a TypeScript enum member
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* @param {ASTNode} node The node to be validated
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* @returns {boolean} True if the node parent is a TypeScript enum member
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*/
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function isParentTSEnumDeclaration(node) {
35+
return node.parent.type === "TSEnumMember";
36+
}
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/**
39+
* Checks if the node is a valid TypeScript numeric literal type.
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* @param {ASTNode} node The node to be validated
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* @returns {boolean} True if the node is a TypeScript numeric literal type
42+
*/
43+
function isTSNumericLiteralType(node) {
44+
let ancestor = node.parent;
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// Go up while we're part of a type union
47+
while (ancestor.parent.type === "TSUnionType") {
48+
ancestor = ancestor.parent;
49+
}
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// Check if the final ancestor is in a type alias declaration
52+
return ancestor.parent.type === "TSTypeAliasDeclaration";
53+
}
54+
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/**
56+
* Checks if the node parent is a readonly class property
57+
* @param {ASTNode} node The node to be validated
58+
* @returns {boolean} True if the node parent is a readonly class property
59+
*/
60+
function isParentTSReadonlyPropertyDefinition(node) {
61+
if (node.parent?.type === "PropertyDefinition" && node.parent.readonly) {
62+
return true;
63+
}
64+
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return false;
66+
}
67+
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/**
69+
* Checks if the node is part of a type indexed access (eg. Foo[4])
70+
* @param {ASTNode} node The node to be validated
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* @returns {boolean} True if the node is part of an indexed access
72+
*/
73+
function isAncestorTSIndexedAccessType(node) {
74+
let ancestor = node.parent;
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/*
77+
* Go up another level while we're part of a type union (eg. 1 | 2) or
78+
* intersection (eg. 1 & 2)
79+
*/
80+
while (
81+
ancestor.parent.type === "TSUnionType" ||
82+
ancestor.parent.type === "TSIntersectionType"
83+
) {
84+
ancestor = ancestor.parent;
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}
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return ancestor.parent.type === "TSIndexedAccessType";
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}
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2990
/** @type {import('../types').Rule.RuleModule} */
3091
module.exports = {
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meta: {
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type: "suggestion",
94+
dialects: ["typescript", "javascript"],
95+
language: "javascript",
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docs: {
3598
description: "Disallow magic numbers",
@@ -75,6 +138,22 @@ module.exports = {
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type: "boolean",
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default: false,
77140
},
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ignoreEnums: {
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type: "boolean",
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default: false,
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},
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ignoreNumericLiteralTypes: {
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type: "boolean",
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default: false,
148+
},
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ignoreReadonlyClassProperties: {
150+
type: "boolean",
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default: false,
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},
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ignoreTypeIndexes: {
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type: "boolean",
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default: false,
156+
},
78157
},
79158
additionalProperties: false,
80159
},
@@ -94,7 +173,12 @@ module.exports = {
94173
ignoreArrayIndexes = !!config.ignoreArrayIndexes,
95174
ignoreDefaultValues = !!config.ignoreDefaultValues,
96175
ignoreClassFieldInitialValues =
97-
!!config.ignoreClassFieldInitialValues;
176+
!!config.ignoreClassFieldInitialValues,
177+
ignoreEnums = !!config.ignoreEnums,
178+
ignoreNumericLiteralTypes = !!config.ignoreNumericLiteralTypes,
179+
ignoreReadonlyClassProperties =
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!!config.ignoreReadonlyClassProperties,
181+
ignoreTypeIndexes = !!config.ignoreTypeIndexes;
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99183
const okTypes = detectObjects
100184
? []
@@ -217,14 +301,15 @@ module.exports = {
217301
let value;
218302
let raw;
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220-
// Treat unary minus as a part of the number
304+
// Treat unary minus/plus as a part of the number
221305
if (
222306
node.parent.type === "UnaryExpression" &&
223-
node.parent.operator === "-"
307+
["-", "+"].includes(node.parent.operator)
224308
) {
225309
fullNumberNode = node.parent;
226-
value = -node.value;
227-
raw = `-${node.raw}`;
310+
value =
311+
node.parent.operator === "-" ? -node.value : node.value;
312+
raw = `${node.parent.operator}${node.raw}`;
228313
} else {
229314
fullNumberNode = node;
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value = node.value;
@@ -239,6 +324,14 @@ module.exports = {
239324
(ignoreDefaultValues && isDefaultValue(fullNumberNode)) ||
240325
(ignoreClassFieldInitialValues &&
241326
isClassFieldInitialValue(fullNumberNode)) ||
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(ignoreEnums &&
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isParentTSEnumDeclaration(fullNumberNode)) ||
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(ignoreNumericLiteralTypes &&
330+
isTSNumericLiteralType(fullNumberNode)) ||
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(ignoreTypeIndexes &&
332+
isAncestorTSIndexedAccessType(fullNumberNode)) ||
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(ignoreReadonlyClassProperties &&
334+
isParentTSReadonlyPropertyDefinition(fullNumberNode)) ||
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isParseIntRadix(fullNumberNode) ||
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isJSXNumber(fullNumberNode) ||
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(ignoreArrayIndexes && isArrayIndex(fullNumberNode, value))

‎lib/types/rules.d.ts‎

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@@ -2858,6 +2858,22 @@ export interface ESLintRules extends Linter.RulesRecord {
28582858
* @default false
28592859
*/
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detectObjects: boolean;
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/**
2862+
* @default false
2863+
*/
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ignoreEnums: boolean;
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/**
2866+
* @default false
2867+
*/
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ignoreNumericLiteralTypes: boolean;
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/**
2870+
* @default false
2871+
*/
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ignoreReadonlyClassProperties: boolean;
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/**
2874+
* @default false
2875+
*/
2876+
ignoreTypeIndexes: boolean;
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}>,
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]
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>;

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