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jakebaileyjakebailey
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Backport tsog PR 3301 for testing
1 parent 0844c43 commit 96faf0a

4 files changed

Lines changed: 160 additions & 3 deletions

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‎src/compiler/checker.ts‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -25499,12 +25499,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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function getSingleCommonSupertype(types: Type[]) {
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// First, find the leftmost type for which no type to the right is a strict supertype, and if that
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// type is a strict supertype of all other candidates, return it. Otherwise, return the leftmost type
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// for which no type to the right is a (regular) supertype.
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// type is a strict supertype of all other candidates, return it. Otherwise, use asymmetric
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// assignability as a tiebreaker (i.e. only switch candidates when the assignment is one-way).
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const candidate = reduceLeft(types, (s, t) => isTypeStrictSubtypeOf(s, t) ? t : s)!;
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return every(types, t => t === candidate || isTypeStrictSubtypeOf(t, candidate)) ?
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candidate :
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reduceLeft(types, (s, t) => isTypeSubtypeOf(s, t) ? t : s)!;
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reduceLeft(types, (s, t) => isTypeAssignableTo(s, t) && !isTypeAssignableTo(t, s) ? t : s)!;
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}
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// Return the leftmost type for which no type to the right is a subtype.

‎tests/baselines/reference/discriminatedUnionFlatMap.symbols‎

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//// [tests/cases/compiler/discriminatedUnionFlatMap.ts] ////
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=== discriminatedUnionFlatMap.ts ===
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// https://github.com/microsoft/typescript-go/issues/1057
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export type InputOp = { op: "add" } | { op: "remove"; value?: Array<unknown> };
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>InputOp : Symbol(InputOp, Decl(discriminatedUnionFlatMap.ts, 0, 0))
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>op : Symbol(op, Decl(discriminatedUnionFlatMap.ts, 2, 23))
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>op : Symbol(op, Decl(discriminatedUnionFlatMap.ts, 2, 39))
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>value : Symbol(value, Decl(discriminatedUnionFlatMap.ts, 2, 53))
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>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 2 more)
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export type OutputOp = { op: "add" | "remove" };
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>OutputOp : Symbol(OutputOp, Decl(discriminatedUnionFlatMap.ts, 2, 79))
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>op : Symbol(op, Decl(discriminatedUnionFlatMap.ts, 3, 24))
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export function f(operations: InputOp[]): OutputOp[] {
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>f : Symbol(f, Decl(discriminatedUnionFlatMap.ts, 3, 48))
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>operations : Symbol(operations, Decl(discriminatedUnionFlatMap.ts, 5, 18))
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>InputOp : Symbol(InputOp, Decl(discriminatedUnionFlatMap.ts, 0, 0))
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>OutputOp : Symbol(OutputOp, Decl(discriminatedUnionFlatMap.ts, 2, 79))
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return operations.flatMap((operation) => {
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>operations.flatMap : Symbol(Array.flatMap, Decl(lib.es2019.array.d.ts, --, --))
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>operations : Symbol(operations, Decl(discriminatedUnionFlatMap.ts, 5, 18))
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>flatMap : Symbol(Array.flatMap, Decl(lib.es2019.array.d.ts, --, --))
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>operation : Symbol(operation, Decl(discriminatedUnionFlatMap.ts, 6, 31))
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if (operation.op === "remove" && operation.value) {
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>operation.op : Symbol(op, Decl(discriminatedUnionFlatMap.ts, 2, 23), Decl(discriminatedUnionFlatMap.ts, 2, 39))
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>operation : Symbol(operation, Decl(discriminatedUnionFlatMap.ts, 6, 31))
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>op : Symbol(op, Decl(discriminatedUnionFlatMap.ts, 2, 23), Decl(discriminatedUnionFlatMap.ts, 2, 39))
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>operation.value : Symbol(value, Decl(discriminatedUnionFlatMap.ts, 2, 53))
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>operation : Symbol(operation, Decl(discriminatedUnionFlatMap.ts, 6, 31))
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>value : Symbol(value, Decl(discriminatedUnionFlatMap.ts, 2, 53))
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return [].map(() => ({ op: "remove" }));
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>[].map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
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>map : Symbol(Array.map, Decl(lib.es5.d.ts, --, --))
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>op : Symbol(op, Decl(discriminatedUnionFlatMap.ts, 8, 34))
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} else {
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return [operation];
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>operation : Symbol(operation, Decl(discriminatedUnionFlatMap.ts, 6, 31))
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}
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});
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}
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‎tests/baselines/reference/discriminatedUnionFlatMap.types‎

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//// [tests/cases/compiler/discriminatedUnionFlatMap.ts] ////
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=== discriminatedUnionFlatMap.ts ===
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// https://github.com/microsoft/typescript-go/issues/1057
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export type InputOp = { op: "add" } | { op: "remove"; value?: Array<unknown> };
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>InputOp : InputOp
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> : ^^^^^^^
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>op : "add"
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> : ^^^^^
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>op : "remove"
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> : ^^^^^^^^
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>value : unknown[] | undefined
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> : ^^^^^^^^^^^^^^^^^^^^^
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export type OutputOp = { op: "add" | "remove" };
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>OutputOp : OutputOp
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> : ^^^^^^^^
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>op : "add" | "remove"
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> : ^^^^^^^^^^^^^^^^
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export function f(operations: InputOp[]): OutputOp[] {
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>f : (operations: InputOp[]) => OutputOp[]
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> : ^ ^^ ^^^^^
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>operations : InputOp[]
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> : ^^^^^^^^^
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return operations.flatMap((operation) => {
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>operations.flatMap((operation) => { if (operation.op === "remove" && operation.value) { return [].map(() => ({ op: "remove" })); } else { return [operation]; } }) : InputOp[]
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> : ^^^^^^^^^
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>operations.flatMap : <U, This = undefined>(callback: (this: This, value: InputOp, index: number, array: InputOp[]) => U | readonly U[], thisArg?: This | undefined) => U[]
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> : ^ ^^ ^^^^^^^^^^^^^^ ^^^ ^^^^^^^^ ^^^^^^^^^^^ ^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>operations : InputOp[]
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> : ^^^^^^^^^
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>flatMap : <U, This = undefined>(callback: (this: This, value: InputOp, index: number, array: InputOp[]) => U | readonly U[], thisArg?: This | undefined) => U[]
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> : ^ ^^ ^^^^^^^^^^^^^^ ^^^ ^^^^^^^^ ^^^^^^^^^^^ ^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>(operation) => { if (operation.op === "remove" && operation.value) { return [].map(() => ({ op: "remove" })); } else { return [operation]; } } : (this: undefined, operation: InputOp) => InputOp[] | { op: "remove"; }[]
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> : ^ ^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>operation : InputOp
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> : ^^^^^^^
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if (operation.op === "remove" && operation.value) {
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>operation.op === "remove" && operation.value : false | unknown[] | undefined
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> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>operation.op === "remove" : boolean
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> : ^^^^^^^
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>operation.op : "add" | "remove"
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> : ^^^^^^^^^^^^^^^^
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>operation : InputOp
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> : ^^^^^^^
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>op : "add" | "remove"
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> : ^^^^^^^^^^^^^^^^
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>"remove" : "remove"
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> : ^^^^^^^^
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>operation.value : unknown[] | undefined
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> : ^^^^^^^^^^^^^^^^^^^^^
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>operation : { op: "remove"; value?: Array<unknown>; }
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> : ^^^^^^ ^^^^^^^^^^ ^^^
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>value : unknown[] | undefined
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> : ^^^^^^^^^^^^^^^^^^^^^
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return [].map(() => ({ op: "remove" }));
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>[].map(() => ({ op: "remove" })) : { op: "remove"; }[]
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> : ^^^^^^^^^^^^^^^^^^^
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>[].map : <U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[]
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> : ^ ^^ ^^^ ^^^^^^^^^ ^^ ^^ ^^^^^^^^^^^^^^^^^ ^^^ ^^^^^^^^
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>[] : never[]
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> : ^^^^^^^
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>map : <U>(callbackfn: (value: never, index: number, array: never[]) => U, thisArg?: any) => U[]
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> : ^ ^^ ^^^ ^^^^^^^^^ ^^ ^^ ^^^^^^^^^^^^^^^^^ ^^^ ^^^^^^^^
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>() => ({ op: "remove" }) : () => { op: "remove"; }
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> : ^^^^^^^^^^^^^^^^^^^^^^^
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>({ op: "remove" }) : { op: "remove"; }
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> : ^^^^^^^^^^^^^^^^^
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>{ op: "remove" } : { op: "remove"; }
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> : ^^^^^^^^^^^^^^^^^
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>op : "remove"
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> : ^^^^^^^^
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>"remove" : "remove"
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> : ^^^^^^^^
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} else {
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return [operation];
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>[operation] : InputOp[]
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> : ^^^^^^^^^
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>operation : InputOp
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> : ^^^^^^^
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}
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});
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}
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‎tests/cases/compiler/discriminatedUnionFlatMap.ts‎

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// @strict: true
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// @noEmit: true
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// @lib: es2019
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// https://github.com/microsoft/typescript-go/issues/1057
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export type InputOp = { op: "add" } | { op: "remove"; value?: Array<unknown> };
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export type OutputOp = { op: "add" | "remove" };
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export function f(operations: InputOp[]): OutputOp[] {
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return operations.flatMap((operation) => {
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if (operation.op === "remove" && operation.value) {
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return [].map(() => ({ op: "remove" }));
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} else {
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return [operation];
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}
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});
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}

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