mgr/dashboard: improve typing in Ceph services

Signed-off-by: Patrick Seidensal <[email protected]>

src/pybind/mgr/dashboard/services/ceph_service.py

@@ -12,7 +12,7 @@
 from ..exceptions import DashboardException
 
 try:
-    from typing import Any, Dict, Union
+    from typing import Any, Dict, Union, Optional
 except ImportError:
     pass  # For typing only
 
@@ -158,8 +158,9 @@ def get_pool_pg_status(cls, pool_name):
             return {}
         return mgr.get("pg_summary")['by_pool'][pool['pool'].__str__()]
 
-    @classmethod
-    def send_command(cls, srv_type, prefix, srv_spec='', **kwargs):
+    @staticmethod
+    def send_command(srv_type, prefix, srv_spec='', **kwargs):
+        # type: (str, str, Optional[str], Any) -> Any
         """
         :type prefix: str
         :param srv_type: mon |
@@ -247,14 +248,14 @@ def _get_smart_data_by_device(device):
 
     @staticmethod
     def get_devices_by_host(hostname):
-        # (str) -> dict
+        # type: (str) -> dict
         return CephService.send_command('mon',
                                         'device ls-by-host',
                                         host=hostname)
 
     @staticmethod
     def get_devices_by_daemon(daemon_type, daemon_id):
-        # (str, str) -> dict
+        # type: (str, str) -> dict
         return CephService.send_command('mon',
                                         'device ls-by-daemon',
                                         who='{}.{}'.format(