Single Listing Endpoint
Use this endpoint for accessing a single listing. When you make a search to the `/properties` endpoint, each listing in the response will contain a unique `mlsId` field which should be used to request that listing on this route. The `mlsId` field is a unique identifier for a listing which is specific to the SimplyRETS API only. It is different from the `listingId` field is the public number given to a listing by the MLS and is not used here.