Update wtw.py

wsimod/nodes/wtw.py

@@ -9,7 +9,12 @@
 from typing import Any, Dict
 
 class WTW(Node):
-    """"""
+    """A generic Water Treatment Works (WTW) node.
+    
+    This class is a generic water treatment works node. It is intended to be
+    subclassed into freshwater and wastewater treatment works (FWTW and WWTW
+    respectively).
+    """
 
     def __init__(
         self,
@@ -122,7 +127,12 @@ def liquor_multiplier(self, value):
         self.process_parameters["volume"]["constant"] = self.calculate_volume()
 
     def apply_overrides(self, overrides = Dict[str, Any]):
-        """Apply overrides to the process parameters and liquor multipliers.
+        """Override parameters.
+
+        Enables a user to override any of the following parameters: 
+        percent_solids, treatment_throughput_capacity, process_parameters (the
+        entire dict does not need to be redefined, only changed values need to
+        be included), liquor_multiplier (as with process_parameters).
 
         Args:
             overrides (Dict[str, Any]): Dict describing which parameters should
@@ -211,7 +221,7 @@ def end_timestep(self):
 
 
 class WWTW(WTW):
-    """"""
+    """Wastewater Treatment Works (WWTW) node."""
 
     def __init__(
         self,
@@ -288,6 +298,13 @@ def __init__(
 
     def apply_overrides(self, overrides=Dict[str, Any]):
         """Apply overrides to the stormwater tank and WWTW.
+
+        Enables a user to override any parameter of the stormwater tank, and
+        then calls any overrides in WTW.
+        
+        Args:
+            overrides (Dict[str, Any]): Dict describing which parameters should
+                be overridden (keys) and new values (values). Defaults to {}.
         """
         self.stormwater_storage_capacity = overrides.pop(
             "stormwater_storage_capacity",