style: simplify

python/hypy/hydrolocation/nwis_location.py

@@ -10,10 +10,13 @@
     from numpy import datetime64
     from datetime import datetime
     from shapely.geometry import Point
+
 class NWISLocation(HydroLocation):
     """
     An NWIS subclass of HydroLocation
     """
+    __slots__ = ("_station_id",)
+
     def __init__(self,
                 station_id: str,
                 realized_nexus: str,

python/hypy/nexus.py

@@ -6,7 +6,7 @@
     from .catchment import Catchment, Catchments_Collection
     from .hydrolocation.hydrolocation import HydroLocation
 
-class Nexus():
+class Nexus:
     """
     Implementation of the HY Features Nexus concept.
     """