Angular Pipe CEP Brasileiro

cep.br.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({ name: 'CEP' })
export class CEPPipe implements PipeTransform {
    transform(cep: number) {
        var sCep = cep.toString()
        var fCep = sCep.substring(0,5)+'-'+sCep.substring(5)
        return fCep;
    }
}