first pass of trying to work through deriving annual growth on bills, what info I need, etc. definitely not even close to finished

bills.py

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+from db import get_bill_data, get_bill_types, set_bill_type_growth
+
+def derive_bill_data():
+  bd=get_bill_data()
+  bt=get_bill_types()
+  water_id = None
+  for t in bt:
+    if t['name'] == "Water":
+        water_id = t['id']
+
+  if not water_id:
+    return
+  total={}
+  total[water_id]={}
+  for yr in [2022, 2023, 2024]:
+      print( f"water_id={water_id}")
+      total[water_id][yr] = 0
+      for b in bd:
+        if b['bill_type_id'] == water_id and str(yr) in b['bill_date']:
+            total[water_id][yr] += b['amount']
+            print( f"{yr} => {b['bill_date']} -- {b['amount']}" )
+      print( f"total for water in {yr} is {total[water_id][yr]}" )
+
+  # once we have all yr totals:
+  growth = {}
+  growth[water_id] = {}
+  max_growth = {}
+  avg_growth = {}
+  max_growth[water_id] = 0
+  avg_growth[water_id] = 0
+  count = 0
+  for yr in [2023, 2024]:
+    growth[water_id][yr] = (total[water_id][yr] - total[water_id][yr-1]) / total[water_id][yr-1] * 100
+    avg_growth[water_id] += growth[water_id][yr]
+    count += 1
+    if growth[water_id][yr] > max_growth[water_id]:
+        max_growth[water_id] = growth[water_id][yr]
+    print( f"growth from {yr} to {yr-1} = {growth}%")
+  print( f"Max growth was: {max_growth[water_id]}" )
+  print( f"Avg growth is: {avg_growth[water_id]/count}" )
+  set_bill_type_growth( water_id, avg_growth[water_id]/count )