import { DirectionArrowSymbol , isDirectionArrowSymbol } from './direction-arrow-symbol.enum' ; import { DirectionCardinalGeographicLetter , isDirectionCardinalGeographicLetter , } from './direction-cardinal-geographic-letter.enum' ; import { DirectionCardinalLiteralLetter , isDirectionCardinalLiteralLetter , } from './direction-cardinal-literal-letter.enum' ; export type DirectionMarker = DirectionArrowSymbol | DirectionCardinalGeographicLetter | DirectionCardinalLiteralLetter ; export const isDirectionMarker = ( marker ) : marker is DirectionMarker => isDirectionArrowSymbol ( marker ) || isDirectionCardinalGeographicLetter ( marker ) || isDirectionCardinalLiteralLetter ( marker ) ;