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const SUSPENSE_PROMISE = Symbol()
// Not exported for public APIexport type SuspensePromise = Promise<void> & {  [SUSPENSE_PROMISE]: {    o: Promise<void> // original promise    c: (() => void) | null // cancel promise (null if already cancelled)  }}
export const isSuspensePromise = (  promise: Promise<void>): promise is SuspensePromise =>  !!(promise as SuspensePromise)[SUSPENSE_PROMISE]
export const isSuspensePromiseAlreadyCancelled = (  suspensePromise: SuspensePromise) => !suspensePromise[SUSPENSE_PROMISE].c
export const cancelSuspensePromise = (suspensePromise: SuspensePromise) => {  suspensePromise[SUSPENSE_PROMISE].c?.()}
// Note: this is a special equality functionexport const isEqualSuspensePromise = (  oldSuspensePromise: SuspensePromise,  newSuspensePromise: SuspensePromise): boolean => {  const oldOriginalPromise = oldSuspensePromise[SUSPENSE_PROMISE].o  const newOriginalPromise = newSuspensePromise[SUSPENSE_PROMISE].o  return (    oldOriginalPromise === newOriginalPromise ||    oldSuspensePromise === newOriginalPromise ||    (isSuspensePromise(oldOriginalPromise) &&      isEqualSuspensePromise(oldOriginalPromise, newSuspensePromise))  )}
export const createSuspensePromise = (  promise: Promise<void>): SuspensePromise => {  const objectToAttach = {    o: promise, // original promise    c: null as (() => void) | null, // cancel promise  }  const suspensePromise = new Promise<void>((resolve) => {    objectToAttach.c = () => {      objectToAttach.c = null      resolve()    }    promise.then(objectToAttach.c, objectToAttach.c)  }) as SuspensePromise  suspensePromise[SUSPENSE_PROMISE] = objectToAttach  return suspensePromise}