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const canElideFrames = 'captureStackTrace' in Errorconst startStackFrames = new WeakMap()
interface Result {  name: 'AssertionError' | 'AssertionResult'  ok: boolean  toJSON(...args: unknown[]): Record<string, unknown>}
export class AssertionError<T> extends Error implements Result {  [key: string]: unknown
  get name(): 'AssertionError' {    return 'AssertionError'  }
  get ok() {    return false  }
  constructor(public message = 'Unspecified AssertionError', props?: T, ssf?: Function) {    super(message)    if (canElideFrames && ssf) startStackFrames.set(this, ssf)    for (const key in props) {      if (!(key in this)) {        // @ts-ignore        this[key] = props[key];      }    }  }
  get stack() {    if (canElideFrames) {      return (Error as any).captureStackTrace(this, startStackFrames.get(this) || AssertionError);    } else {      return super.stack    }  }
  toJSON(stack: boolean): Record<string, unknown> {    return {      ...this,      name: this.name,      message: this.message,      ok: false,      // include stack if exists and not turned off      stack: stack !== false ? this.stack : undefined,    }  }
}
export class AssertionResult<T> implements Result {  [key: string]: unknown
  get name(): 'AssertionResult' {    return 'AssertionResult'  }
  get ok() {    return true  }
  constructor(props?: T) {    for (const key in props) {      if (!(key in this)) {        // @ts-ignore        this[key] = props[key];      }    }  }
  toJSON(): Record<string, unknown> {    return {      ...this,      name: this.name,      ok: this.ok,    }  }}