import { Diff } from './Diff' ; const equalDiffSymbol = Symbol ( 'equal diff' ) ; const equalDiff = function ( parameters ) : EqualDiff { return { kind : equalDiffSymbol , cost : 0 , ... parameters } ; } ; interface EqualDiff extends Diff { kind : typeof equalDiffSymbol ; value : any ; } const isEqualDiff = function ( diff ) : diff is EqualDiff { return 'kind' in diff && diff . kind === equalDiffSymbol ; } ; export type { EqualDiff } ; export { isEqualDiff , equalDiff } ;