diff --git a/src/Year_2015/P7.py b/src/Year_2015/P7.py
index 62c57bf..d4d21bd 100644
--- a/src/Year_2015/P7.py
+++ b/src/Year_2015/P7.py
@@ -81,7 +81,7 @@ def rshift_gate(x: int, y: int) -> int:
 
 
 @functools.lru_cache()
-def rec_solve(node):
+def rec_solve(node: str) -> int:
     if node.isdigit():
         return int(node)
     instruction = gates[node]
@@ -109,7 +109,7 @@ for instr in instructions:
     gates[rhs.strip()] = lhs.strip().split()
 
 
-def part_1():
+def part_1() -> None:
     signal_a = rec_solve("a")
     print(f"Signal A will be ultimately {signal_a}")
 
@@ -121,7 +121,7 @@ def part_1():
 # provided to wire a?
 
 
-def part_2():
+def part_2() -> None:
     signal_a = rec_solve("a")
     rec_solve.cache_clear()
     gates["b"] = [str(signal_a)]