diff --git a/src/agents/__init__.py b/src/agents/__init__.py
index 742365a..72829f9 100644
--- a/src/agents/__init__.py
+++ b/src/agents/__init__.py
@@ -2,3 +2,10 @@
 from .randomized_reflex_agent import RandomizedReflexAgent
 from .reflex_vacuum_agent import reflex_vacuum_agent
 from .simple_reflex_agent import SimpleReflexAgent
+
+__all__ = [
+    "ModelBasedReflexAgent",
+    "RandomizedReflexAgent",
+    "reflex_vacuum_agent",
+    "SimpleReflexAgent",
+]
diff --git a/src/algorithms/__init__.py b/src/algorithms/__init__.py
index 1dcd828..7aa46f2 100644
--- a/src/algorithms/__init__.py
+++ b/src/algorithms/__init__.py
@@ -5,3 +5,15 @@
 from .expand import expand
 from .iterative_deepening_search import iterative_deepening_search
 from .ucs import uniform_cost_search
+
+__all__ = [
+    "best_first_search",
+    "bibf_search",
+    "breadth_first_search",
+    "depth",
+    "depth_limited_search",
+    "is_cycle",
+    "expand",
+    "iterative_deepening_search",
+    "uniform_cost_search",
+]
diff --git a/src/algorithms/depth_limited_search.py b/src/algorithms/depth_limited_search.py
index e93c5ed..d996d2a 100644
--- a/src/algorithms/depth_limited_search.py
+++ b/src/algorithms/depth_limited_search.py
@@ -47,7 +47,7 @@ def is_cycle(node: Node) -> bool:
     return False
 
 
-def depth_limited_search(problem: Problem, l: int) -> Node | str | None:
+def depth_limited_search(problem: Problem, l_depth: int) -> Node | str | None:
     """Expands the root node, the next child, repeating this process
     until the depth limit is reached, then backtracking to the next
     successor of the root. This process is repeated until a goal is
@@ -70,7 +70,7 @@ def depth_limited_search(problem: Problem, l: int) -> Node | str | None:
         if problem.is_goal(node.state):
             return node
 
-        if depth(node) > l:
+        if depth(node) > l_depth:
             result = "cutoff"
         elif not is_cycle(node):
             for child in expand(problem, node):
diff --git a/src/data_structures/__init__.py b/src/data_structures/__init__.py
index 31b45db..cfd3d52 100644
--- a/src/data_structures/__init__.py
+++ b/src/data_structures/__init__.py
@@ -4,3 +4,12 @@
 from .priority_queue import PriorityQueue
 from .problem import Problem
 from .sensor import Sensor
+
+__all__ = [
+    "Actuator",
+    "Environment",
+    "Node",
+    "PriorityQueue",
+    "Problem",
+    "Sensor",
+]
diff --git a/test/data_structures/test_priority_queue.py b/test/data_structures/test_priority_queue.py
index f576aea..8e0c032 100644
--- a/test/data_structures/test_priority_queue.py
+++ b/test/data_structures/test_priority_queue.py
@@ -38,7 +38,7 @@ def test_pop(self) -> None:
         assert self._queue.is_empty()
 
     def test_top(self) -> None:
-        assert self._queue.top() == None
+        assert self._queue.top() is None
 
         A = Node(state={}, parent=None, action="None", path_cost=0)
         self._queue.add(A)
@@ -52,13 +52,13 @@ def test_top(self) -> None:
 
     def test_add(self) -> None:
         while not self._queue.is_empty():
-            node = self._queue.pop()
+            _ = self._queue.pop()
 
         A = Node(state={}, parent=None, action="None", path_cost=0)
         B = Node(state={}, parent=None, action="None", path_cost=1)
         C = Node(state={}, parent=None, action="None", path_cost=2)
 
-        assert self._queue.top() == None
+        assert self._queue.top() is None
 
         self._queue.add(C)