diff --git a/.github/workflows/check-python.yml b/.github/workflows/check-python.yml
index 5878a9f5..21fa84da 100644
--- a/.github/workflows/check-python.yml
+++ b/.github/workflows/check-python.yml
@@ -28,4 +28,4 @@ jobs:
         mypy . --exclude 79_Slalom --exclude 27_Civil_War --exclude 38_Fur_Trader --exclude 81_Splat --exclude 09_Battle --exclude 40_Gomoko --exclude 36_Flip_Flop --exclude 43_Hammurabi --exclude 04_Awari --exclude 78_Sine_Wave --exclude 77_Salvo --exclude 34_Digits --exclude 17_Bullfight --exclude 16_Bug
     - name: Test with flake8
       run: |
-        flake8 . --ignore E501,W503,E203,E731
+        flake8 . --ignore E501,W503,E203,E731,B011
diff --git a/00_Utilities/python/ci-requirements.in b/00_Utilities/python/ci-requirements.in
index baf71ecc..7efd7199 100644
--- a/00_Utilities/python/ci-requirements.in
+++ b/00_Utilities/python/ci-requirements.in
@@ -1,3 +1,4 @@
 pytest
 flake8
+flake8-bugbear
 mypy
diff --git a/00_Utilities/python/ci-requirements.txt b/00_Utilities/python/ci-requirements.txt
index 549785af..56923d59 100644
--- a/00_Utilities/python/ci-requirements.txt
+++ b/00_Utilities/python/ci-requirements.txt
@@ -5,8 +5,14 @@
 #    pip-compile ci-requirements.in
 #
 attrs==21.4.0
-    # via pytest
+    # via
+    #   flake8-bugbear
+    #   pytest
 flake8==4.0.1
+    # via
+    #   -r ci-requirements.in
+    #   flake8-bugbear
+flake8-bugbear==22.1.11
     # via -r ci-requirements.in
 iniconfig==1.1.1
     # via pytest
diff --git a/04_Awari/python/awari.py b/04_Awari/python/awari.py
index f648a5c8..4398cb3f 100644
--- a/04_Awari/python/awari.py
+++ b/04_Awari/python/awari.py
@@ -292,7 +292,7 @@ def do_move(m, home, board):
     move_stones = board[m]
     board[m] = 0
 
-    for stones in range(move_stones, 0, -1):
+    for _stones in range(move_stones, 0, -1):
         m = m + 1
         if m > 13:
             m = m - 14
diff --git a/06_Banner/python/banner.py b/06_Banner/python/banner.py
index 7ef1d507..cd32e87a 100644
--- a/06_Banner/python/banner.py
+++ b/06_Banner/python/banner.py
@@ -97,11 +97,11 @@ def print_banner():
                         if s[u] == 1:
                             f[u] = 8 - k
                             break
-                for t1 in range(1, x + 1):
+                for _t1 in range(1, x + 1):
                     line_str = " " * int((63 - 4.5 * y) * g1 / len(xStr) + 1)
                     for b in range(0, f[u] + 1):
                         if j[b] == 0:
-                            for i in range(1, y + 1):
+                            for _ in range(1, y + 1):
                                 line_str = line_str + " " * len(xStr)
                         else:
                             line_str = line_str + xStr * y
diff --git a/14_Bowling/python/bowling.py b/14_Bowling/python/bowling.py
index a5d8f079..b2fdd500 100644
--- a/14_Bowling/python/bowling.py
+++ b/14_Bowling/python/bowling.py
@@ -66,7 +66,7 @@ class Player:
             print(f"Extra rolls for {self.name}")
             pins = [0] * 10  # reset the pins
             score = 0
-            for ball in range(extra):
+            for _ball in range(extra):
                 if score == 10:
                     pins = [0] * 10
                 simulateRoll(pins)
diff --git a/15_Boxing/python/boxing.py b/15_Boxing/python/boxing.py
index fe624101..61c2ef43 100755
--- a/15_Boxing/python/boxing.py
+++ b/15_Boxing/python/boxing.py
@@ -48,7 +48,7 @@ def play():
         if opponent_score >= 2 or player_score >= 2:
             break
 
-        for action in range(7):
+        for _action in range(7):
             if random.randint(1, 10) > 5:
                 # opponent swings
                 punch = random.randint(1, 4)
diff --git a/16_Bug/python/Bug.py b/16_Bug/python/Bug.py
index 819e50ef..71344b4c 100644
--- a/16_Bug/python/Bug.py
+++ b/16_Bug/python/Bug.py
@@ -1,4 +1,5 @@
 import random
+import time
 
 
 def print_n_whitespaces(n: int):
@@ -179,8 +180,7 @@ while not (Y > 0):
     # 970
     X = random.randint(1, 6)
     print()
-    for delay in range(2000):
-        pass
+    time.sleep(2)
 
     print("I ROLLED A", X)
     if X == 1:
diff --git a/21_Calendar/python/calendar.py b/21_Calendar/python/calendar.py
index e954d7c7..5332f201 100644
--- a/21_Calendar/python/calendar.py
+++ b/21_Calendar/python/calendar.py
@@ -109,9 +109,9 @@ def calendar(weekday, leap_year):
         print(days)
         print(sep)
 
-        for w in range(1, 7):
+        for _ in range(1, 7):
             print("\n")
-            for g in range(1, 8):
+            for g in range(1, 8):  # noqa
                 d += 1
                 d2 = d - days_count
 
diff --git a/32_Diamond/python/diamond.py b/32_Diamond/python/diamond.py
index a622eb58..4d99dacc 100644
--- a/32_Diamond/python/diamond.py
+++ b/32_Diamond/python/diamond.py
@@ -52,7 +52,7 @@ def main():
 
     count = int(PAGE_WIDTH / width)
 
-    for down in range(count):
+    for _down in range(count):
         print_diamond(1, width, 2, width, count)
         print_diamond(width - 2, 1, -2, width, count)
 
diff --git a/33_Dice/python/dice.py b/33_Dice/python/dice.py
index 9f46a8d8..c86c4bc4 100644
--- a/33_Dice/python/dice.py
+++ b/33_Dice/python/dice.py
@@ -51,7 +51,7 @@ while still_playing:
     n = int(input("How many rolls? "))
 
     # Roll the dice n times
-    for i in range(n):
+    for _ in range(n):
         die1 = random.randint(1, 6)
         die2 = random.randint(1, 6)
         roll_total = die1 + die2
diff --git a/34_Digits/python/Digits.py b/34_Digits/python/Digits.py
index bda172a9..c6d10977 100644
--- a/34_Digits/python/Digits.py
+++ b/34_Digits/python/Digits.py
@@ -93,7 +93,7 @@ def main():
         z2 = 2
         running_correct = 0
 
-        for round in range(1, 4):
+        for _round in range(1, 4):
             valid_numbers = False
             numbers = []
             while not valid_numbers:
diff --git a/43_Hammurabi/python/hamurabi.py b/43_Hammurabi/python/hamurabi.py
index ee224f6d..6bf990df 100644
--- a/43_Hammurabi/python/hamurabi.py
+++ b/43_Hammurabi/python/hamurabi.py
@@ -225,7 +225,7 @@ def main():
         else:
             print("A FANTASTIC PERFORMANCE!!!  CHARLEMANGE, DISRAELI, AND")
             print("JEFFERSON COMBINED COULD NOT HAVE DONE BETTER!\n")
-        for N in range(1, 10):
+        for _ in range(1, 10):
             print("\a")
 
     print("\nSO LONG FOR NOW.\n")
diff --git a/46_Hexapawn/python/hexapawn.py b/46_Hexapawn/python/hexapawn.py
index 3821b2c6..254b5f17 100644
--- a/46_Hexapawn/python/hexapawn.py
+++ b/46_Hexapawn/python/hexapawn.py
@@ -418,9 +418,9 @@ def find_board_index_that_matches_board(board):
         if matches:
             return board_index, is_reversed
 
-    # THE TERMINATION OF THIS LOOP IS IMPOSSIBLE
-    print("ILLEGAL BOARD PATTERN.")
-    assert False
+    # This point should never be reached
+    # In future, mypy might be able to check exhaustiveness via assert_never
+    raise RuntimeError("ILLEGAL BOARD PATTERN.")
 
 
 def pick_computer_move(board):
diff --git a/47_Hi-Lo/python/hilo.py b/47_Hi-Lo/python/hilo.py
index 6341311a..d0badf73 100755
--- a/47_Hi-Lo/python/hilo.py
+++ b/47_Hi-Lo/python/hilo.py
@@ -21,7 +21,7 @@ def play():
         secret = random.randint(1, 100)
         guessed_correctly = False
 
-        for attempt in range(MAX_ATTEMPTS):
+        for _attempt in range(MAX_ATTEMPTS):
             print("YOUR GUESS", end=QUESTION_PROMPT)
             guess = int(input())
 
diff --git a/55_Life/python/life.py b/55_Life/python/life.py
index 71016871..5a8e5062 100644
--- a/55_Life/python/life.py
+++ b/55_Life/python/life.py
@@ -55,7 +55,7 @@ def main():
 
     pattern_height = len(pattern)
     pattern_width = 0
-    for line_num, line in pattern.items():
+    for _line_num, line in pattern.items():
         pattern_width = max(pattern_width, len(line))
 
     min_x = 11 - pattern_height // 2
@@ -94,7 +94,7 @@ def main():
 
         p = 0
         g += 1
-        for x in range(0, min_x):
+        for _ in range(min_x):
             print()
 
         for x in range(min_x, max_x + 1):
@@ -120,7 +120,7 @@ def main():
             print("".join(line))
 
         # line 295
-        for x in range(max_x + 1, MAX_HEIGHT):
+        for _ in range(max_x + 1, MAX_HEIGHT):
             print()
 
         print()
diff --git a/60_Mastermind/python/mastermind.py b/60_Mastermind/python/mastermind.py
index 24897906..fbb94bd1 100644
--- a/60_Mastermind/python/mastermind.py
+++ b/60_Mastermind/python/mastermind.py
@@ -38,7 +38,7 @@ def main():
         print("Guess my combination ...")
         answer = int(possibilities * random.random())
         numeric_answer = [-1] * num_positions
-        for i in range(0, answer):
+        for _ in range(0, answer):
             numeric_answer = get_possibility(numeric_answer)
         # human_readable_answer = make_human_readable(numeric_answer)
         while num_moves < 10 and not turn_over:
@@ -122,7 +122,7 @@ def main():
                     inconsistent_information = True
                 else:
                     numeric_guess = [-1] * num_positions
-                    for i in range(0, guess):
+                    for _ in range(0, guess):
                         numeric_guess = get_possibility(numeric_guess)
                     human_readable_guess = make_human_readable(numeric_guess)
                     print(f"My guess is: {human_readable_guess}")
@@ -142,7 +142,7 @@ def main():
                             if all_possibilities[i] == 0:  # already ruled out
                                 continue
                             numeric_possibility = [-1] * num_positions
-                            for j in range(0, i):
+                            for _ in range(0, i):
                                 numeric_possibility = get_possibility(
                                     numeric_possibility
                                 )
diff --git a/65_Nim/python/Traditional_NIM.py b/65_Nim/python/Traditional_NIM.py
index c7b904ce..ce00b40a 100644
--- a/65_Nim/python/Traditional_NIM.py
+++ b/65_Nim/python/Traditional_NIM.py
@@ -68,7 +68,7 @@ class NIM:
 
     def check_for_win(self):
         sum = 0
-        for k, v in self.piles.items():
+        for v in self.piles.values():
             sum += v
 
         if sum == 0:
diff --git a/69_Pizza/python/pizza.py b/69_Pizza/python/pizza.py
index 0f59262d..0f7d28e2 100644
--- a/69_Pizza/python/pizza.py
+++ b/69_Pizza/python/pizza.py
@@ -28,7 +28,7 @@ def print_header(title):
 
 
 def print_ticks():
-    for t in range(4):
+    for _ in range(4):
         print("-")
 
 
@@ -134,7 +134,7 @@ def deliver_to(customer_index, customer_name, player_name):
 
 
 def play_game(num_turns, player_name):
-    for turn in range(num_turns):
+    for _turn in range(num_turns):
         x = random.randint(1, 4)
         y = random.randint(1, 4)
         customer_index = calculate_customer_index(x, y)
diff --git a/77_Salvo/python/salvo.py b/77_Salvo/python/salvo.py
index 4de418ca..113a97b3 100644
--- a/77_Salvo/python/salvo.py
+++ b/77_Salvo/python/salvo.py
@@ -209,7 +209,7 @@ def generate_ship_coordinates(ship):
     coords = [(start_x, start_y)]
     x_coord = start_x
     y_coord = start_y
-    for i in range(ship_len):
+    for _ in range(ship_len):
         x_coord = x_coord + d_x
         y_coord = y_coord + d_y
         coords.append((x_coord, y_coord))
@@ -356,7 +356,7 @@ def initialize_game():
     for ship in SHIPS:
         print(ship[0])
         list = []
-        for i in range(ship[1]):
+        for _ in range(ship[1]):
             x, y = input_coord()
             list.append((x, y))
         ship_coords.append(list)
@@ -443,7 +443,7 @@ def execute_turn(turn):
         num_shots = num_player_shots
 
     shots = []
-    for shot in range(num_shots):
+    for _shot in range(num_shots):
         valid_shot = False
         x = -1
         y = -1
diff --git a/78_Sine_Wave/python/sinewave.py b/78_Sine_Wave/python/sinewave.py
index edb1e03b..5706225b 100644
--- a/78_Sine_Wave/python/sinewave.py
+++ b/78_Sine_Wave/python/sinewave.py
@@ -46,7 +46,7 @@ radians = 0
 width = CENTER - 1
 
 # "Start long loop"
-for line_num in range(MAX_LINES):
+for _line_num in range(MAX_LINES):
 
     # Get string to display on this line
     curr_string = STRINGS[string_index]
diff --git a/84_Super_Star_Trek/python/superstartrek.py b/84_Super_Star_Trek/python/superstartrek.py
index dcd879f2..01a0631b 100644
--- a/84_Super_Star_Trek/python/superstartrek.py
+++ b/84_Super_Star_Trek/python/superstartrek.py
@@ -882,7 +882,7 @@ def new_quadrant():
     if b3 > 0:
         b4, b5 = find_empty_place()  # position of starbase (sector)
         insert_marker(b4, b5, ">!<")
-    for i in range(s3):
+    for _ in range(s3):
         r1, r2 = find_empty_place()
         insert_marker(r1, r2, " * ")
 
diff --git a/84_Super_Star_Trek/python/superstartrekins.py b/84_Super_Star_Trek/python/superstartrekins.py
index 63736e4c..1dae1749 100644
--- a/84_Super_Star_Trek/python/superstartrekins.py
+++ b/84_Super_Star_Trek/python/superstartrekins.py
@@ -14,7 +14,7 @@ def get_yes_no(prompt):
 
 
 def print_header():
-    for i in range(12):
+    for _ in range(12):
         print()
     t10 = " " * 10
     print(t10 + "*************************************")
@@ -24,7 +24,7 @@ def print_header():
     print(t10 + "*                                   *")
     print(t10 + "*                                   *")
     print(t10 + "*************************************")
-    for i in range(8):
+    for _ in range(8):
         print()
 
 
diff --git a/86_Target/python/target.py b/86_Target/python/target.py
index 055891b0..14b58df5 100644
--- a/86_Target/python/target.py
+++ b/86_Target/python/target.py
@@ -55,7 +55,7 @@ def prompt():
 
 
 def next_target():
-    for i in range(5):
+    for _ in range(5):
         print()
     print("NEXT TARGET...")
     print()
diff --git a/95_Weekday/python/test_weekday.py b/95_Weekday/python/test_weekday.py
new file mode 100644
index 00000000..67185b72
--- /dev/null
+++ b/95_Weekday/python/test_weekday.py
@@ -0,0 +1,49 @@
+import datetime
+
+import pytest
+from weekday import calculate_day_of_week
+
+
+@pytest.mark.parametrize(
+    ("year", "month", "day"),
+    [
+        (yr, m, d)
+        for yr in range(1600, 2021)
+        for m in range(1, 12)
+        for d in range(1, 28)
+    ],
+)
+@pytest.mark.slow  # Those are 125,037 tests!
+def test_weekday_calc(year, month, day):
+    dt = datetime.date(year, month, day)
+    python_weekday = dt.weekday()  # Monday = 0, Sunday = 6
+
+    basic_weekday = calculate_day_of_week(year, month, day)  # Sunday = 1, Saturday = 7
+
+    if ((python_weekday + 2) % 7) != (basic_weekday % 7):
+        print(f"testing yr {year} month {month} day {day}")
+        print(f"python says {python_weekday}")
+        print(f"BASIC says {basic_weekday}")
+        assert False
+
+
+@pytest.mark.parametrize(
+    ("year", "month", "day"),
+    [
+        (yr, m, d)
+        for yr in range(2016, 2021)
+        for m in range(1, 12)
+        for d in range(1, 28)
+    ],
+)
+def test_weekday_calc_4_years(year, month, day):
+    dt = datetime.date(year, month, day)
+    python_weekday = dt.weekday()  # Monday = 0, Sunday = 6
+
+    basic_weekday = calculate_day_of_week(year, month, day)  # Sunday = 1, Saturday = 7
+
+    if ((python_weekday + 2) % 7) != (basic_weekday % 7):
+        print(f"testing yr {year} month {month} day {day}")
+        print(f"python says {python_weekday}")
+        print(f"BASIC says {basic_weekday}")
+        assert False
diff --git a/95_Weekday/python/weekday.py b/95_Weekday/python/weekday.py
index 808e43e5..133cb391 100644
--- a/95_Weekday/python/weekday.py
+++ b/95_Weekday/python/weekday.py
@@ -142,7 +142,7 @@ def calculate_day_of_week(year, month, day):
 
 
 def end():
-    for i in range(5):
+    for _ in range(5):
         print()
 
 
@@ -259,26 +259,6 @@ def main():
     end()
 
 
-def test_weekday_calc(year, month, day):
-    dt = datetime.date(year, month, day)
-    python_weekday = dt.weekday()  # Monday = 0, Sunday = 6
-
-    basic_weekday = calculate_day_of_week(year, month, day)  # Sunday = 1, Saturday = 7
-
-    if ((python_weekday + 2) % 7) != (basic_weekday % 7):
-        print(f"testing yr {year} month {month} day {day}")
-        print(f"python says {python_weekday}")
-        print(f"BASIC says {basic_weekday}")
-        assert False
-
-
-def test_harness():
-    for yr in range(1600, 2021):
-        for m in range(1, 12):
-            for d in range(1, 28):
-                test_weekday_calc(yr, m, d)
-
-
 if __name__ == "__main__":
     main()
 
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 00000000..dff6b32d
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,4 @@
+[tool.pytest.ini_options]
+markers = [
+    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
+]