Add property for accessing SpotWrapper._lease (#83)

* Add property for accessing `SpotWrapper._lease`

* Handle `None` case.

spot_wrapper/wrapper.py

@@ -30,7 +30,7 @@
 from bosdyn.client.graph_nav import GraphNavClient
 from bosdyn.client.gripper_camera_param import GripperCameraParamClient
 from bosdyn.client.image import ImageClient
-from bosdyn.client.lease import LeaseClient, LeaseKeepAlive
+from bosdyn.client.lease import Lease, LeaseClient, LeaseKeepAlive
 from bosdyn.client.license import LicenseClient
 from bosdyn.client.manipulation_api_client import ManipulationApiClient
 from bosdyn.client.map_processing import MapProcessingServiceClient
@@ -850,6 +850,11 @@ def lease(self) -> typing.List[lease_pb2.LeaseResource]:
         """Return latest proto from the _lease_task"""
         return self._lease_task.proto
 
+    @property
+    def lease2(self) -> typing.Optional[Lease]:
+        """Return the most recently `take`n or `acquire`d lease, or `None` if it is `release`d."""
+        return self._lease
+
     @property
     def spot_images(self) -> SpotImages:
         """Return SpotImages instance"""