def endpoint(map)
      map.each { |k, v| apply_endpoint(map, k, v) }
      map
    end
def endpoint(map)
      map.each { |k, v| apply_endpoint(map, k, v) }
      map
    end
endpoint takes a map, and for eack key/value pair, adds a singleton
 method to the map which will fetch that resource (if it looks like a
 URL).