diff --git a/bootstrap.py b/bootstrap.py
index 6f5193e..b6312c3 100644
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -129,7 +129,7 @@ if version is None and not options.accept_buildout_test_releases:
 
     def _final_version(parsed_version):
         for part in parsed_version:
-            if (part[:1] == '*') and (part not in _final_parts):
+            if (part.startswith('*')) and (part not in _final_parts):
                 return False
         return True
     index = setuptools.package_index.PackageIndex(
diff --git a/src/icalendar/prop.py b/src/icalendar/prop.py
index c826584..2331228 100644
--- a/src/icalendar/prop.py
+++ b/src/icalendar/prop.py
@@ -1042,7 +1042,7 @@ class vMonth(int):
                 month_index = int(month)
                 leap = False
             else:
-                if not month[-1] == "L" and month[:-1].isdigit():
+                if month[-1] != "L" and month[:-1].isdigit():
                     raise ValueError(f"Invalid month: {month!r}")
                 month_index = int(month[:-1])
                 leap = True
diff --git a/src/icalendar/tests/prop/test_unit.py b/src/icalendar/tests/prop/test_unit.py
index 87a725b..ce47811 100644
--- a/src/icalendar/tests/prop/test_unit.py
+++ b/src/icalendar/tests/prop/test_unit.py
@@ -24,9 +24,9 @@ class TestProp(unittest.TestCase):
         from icalendar.prop import vDDDLists
 
         dt_list = vDDDLists.from_ical("19960402T010000Z")
-        self.assertTrue(isinstance(dt_list, list))
+        self.assertIsInstance(dt_list, list)
         self.assertEqual(len(dt_list), 1)
-        self.assertTrue(isinstance(dt_list[0], datetime))
+        self.assertIsInstance(dt_list[0], datetime)
         self.assertEqual(str(dt_list[0]), "1996-04-02 01:00:00+00:00")
 
         p = "19960402T010000Z,19960403T010000Z,19960404T010000Z"
@@ -45,7 +45,7 @@ class TestProp(unittest.TestCase):
         self.assertEqual(dt_list.to_ical(), b"20000101T000000,20001111T000000")
 
         instance = vDDDLists([])
-        self.assertFalse(instance == "value")
+        self.assertNotEqual(instance, "value")
 
     def test_prop_vDate(self):
         from icalendar.prop import vDate
@@ -149,7 +149,7 @@ class TestProp(unittest.TestCase):
         self.assertEqual(vRecur(r).to_ical(), b"FREQ=DAILY;COUNT=10;INTERVAL=2")
 
         r = vRecur.from_ical(
-            "FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=-SU;" "BYHOUR=8,9;BYMINUTE=30"
+            "FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=-SU;BYHOUR=8,9;BYMINUTE=30"
         )
         self.assertEqual(
             r,
@@ -165,7 +165,7 @@ class TestProp(unittest.TestCase):
 
         self.assertEqual(
             vRecur(r).to_ical(),
-            b"FREQ=YEARLY;INTERVAL=2;BYMINUTE=30;BYHOUR=8,9;BYDAY=-SU;" b"BYMONTH=1",
+            b"FREQ=YEARLY;INTERVAL=2;BYMINUTE=30;BYHOUR=8,9;BYDAY=-SU;BYMONTH=1",
         )
 
         r = vRecur.from_ical("FREQ=WEEKLY;INTERVAL=1;BYWEEKDAY=TH")
diff --git a/src/icalendar/tests/test_icalendar.py b/src/icalendar/tests/test_icalendar.py
index 36314ae..531eb90 100644
--- a/src/icalendar/tests/test_icalendar.py
+++ b/src/icalendar/tests/test_icalendar.py
@@ -40,7 +40,7 @@ class IcalendarTestCase(unittest.TestCase):
         )
         self.assertEqual(
             Contentlines.from_ical(
-                "A faked\r\n  long line\r\nAnd another " "lin\r\n\te that is folded\r\n"
+                "A faked\r\n  long line\r\nAnd another lin\r\n\te that is folded\r\n"
             ),
             ["A faked long line", "And another line that is folded", ""],
         )
@@ -112,7 +112,7 @@ class IcalendarTestCase(unittest.TestCase):
         )
 
         c = Contentline(
-            "ATTENDEE;CN=Max Rasmussen;ROLE=REQ-PARTICIPANT:" "MAILTO:maxm@example.com"
+            "ATTENDEE;CN=Max Rasmussen;ROLE=REQ-PARTICIPANT:MAILTO:maxm@example.com"
         )
         self.assertEqual(
             c.parts(),
@@ -124,7 +124,7 @@ class IcalendarTestCase(unittest.TestCase):
         )
         self.assertEqual(
             c.to_ical().decode("utf-8"),
-            "ATTENDEE;CN=Max Rasmussen;ROLE=REQ-PARTICIPANT:" "MAILTO:maxm@example.com",
+            "ATTENDEE;CN=Max Rasmussen;ROLE=REQ-PARTICIPANT:MAILTO:maxm@example.com",
         )
 
         # and back again
diff --git a/src/icalendar/tests/test_unit_caselessdict.py b/src/icalendar/tests/test_unit_caselessdict.py
index a3126ee..fefbc4d 100644
--- a/src/icalendar/tests/test_unit_caselessdict.py
+++ b/src/icalendar/tests/test_unit_caselessdict.py
@@ -115,10 +115,10 @@ class TestCaselessdict(unittest.TestCase):
         self.assertEqual(ncd.get("key1"), "val1")
         self.assertEqual(ncd.get("key3", "NOT FOUND"), "val3")
         self.assertEqual(ncd.get("key4", "NOT FOUND"), "NOT FOUND")
-        self.assertTrue("key4" in ncd)
+        self.assertIn("key4", ncd)
 
         del ncd["key4"]
-        self.assertFalse("key4" in ncd)
+        self.assertNotIn("key4", ncd)
 
         ncd.update({"key5": "val5", "KEY6": "val6", "KEY5": "val7"})
         self.assertEqual(ncd["key6"], "val6")
diff --git a/src/icalendar/tests/test_unit_parser_tools.py b/src/icalendar/tests/test_unit_parser_tools.py
index 8eea790..8f3f378 100644
--- a/src/icalendar/tests/test_unit_parser_tools.py
+++ b/src/icalendar/tests/test_unit_parser_tools.py
@@ -12,7 +12,7 @@ class TestParserTools(unittest.TestCase):
         self.assertEqual(to_unicode(b"\xc6\xb5"), "\u01b5")
         self.assertEqual(to_unicode(b"\xc6\xb5", encoding="ascii"), "\u01b5")
         self.assertEqual(to_unicode(1), 1)
-        self.assertEqual(to_unicode(None), None)
+        self.assertIsNone(to_unicode(None))
 
     def test_parser_tools_from_unicode(self):
         self.assertEqual(from_unicode("\u01b5", encoding="ascii"), b"\xc6\xb5")
diff --git a/src/icalendar/tests/test_unit_tools.py b/src/icalendar/tests/test_unit_tools.py
index b396e55..e0d8db4 100644
--- a/src/icalendar/tests/test_unit_tools.py
+++ b/src/icalendar/tests/test_unit_tools.py
@@ -13,20 +13,20 @@ class TestTools(unittest.TestCase):
 
         txt = uid.to_ical()
         length = 15 + 1 + 16 + 1 + 11
-        self.assertTrue(len(txt) == length)
-        self.assertTrue(b"@example.com" in txt)
+        self.assertEqual(len(txt), length)
+        self.assertIn(b"@example.com", txt)
 
         # You should at least insert your own hostname to be more compliant
         uid = g.uid("Example.ORG")
         txt = uid.to_ical()
-        self.assertTrue(len(txt) == length)
-        self.assertTrue(b"@Example.ORG" in txt)
+        self.assertEqual(len(txt), length)
+        self.assertIn(b"@Example.ORG", txt)
 
         # You can also insert a path or similar
         uid = g.uid("Example.ORG", "/path/to/content")
         txt = uid.to_ical()
-        self.assertTrue(len(txt) == length)
-        self.assertTrue(b"-/path/to/content@Example.ORG" in txt)
+        self.assertEqual(len(txt), length)
+        self.assertIn(b"-/path/to/content@Example.ORG", txt)
 
 
 @pytest.mark.parametrize(
diff --git a/src/icalendar/timezone/equivalent_timezone_ids.py b/src/icalendar/timezone/equivalent_timezone_ids.py
index 63da737..d59ad03 100644
--- a/src/icalendar/timezone/equivalent_timezone_ids.py
+++ b/src/icalendar/timezone/equivalent_timezone_ids.py
@@ -123,7 +123,7 @@ def main(
     with file.open("w") as f:
         f.write(f"'''This file is automatically generated by {Path(__file__).name}'''\n")
         f.write("import datetime\n\n")
-        f.write(f"\nlookup = ")
+        f.write("\nlookup = ")
         pprint(lookup, stream=f)
         f.write("\n\n__all__ = ['lookup']\n")
 
diff --git a/src/icalendar/timezone/tzp.py b/src/icalendar/timezone/tzp.py
index 39dbb9c..677d6e9 100644
--- a/src/icalendar/timezone/tzp.py
+++ b/src/icalendar/timezone/tzp.py
@@ -105,16 +105,16 @@ class TZP:
         """
         return tzid.strip("/")
 
-    def timezone(self, id: str) -> Optional[datetime.tzinfo]:
+    def timezone(self, tz_id: str) -> Optional[datetime.tzinfo]:
         """Return a timezone with an id or None if we cannot find it."""
-        _unclean_id = id
-        id = self.clean_timezone_id(id)
-        tz = self.__provider.timezone(id)
+        _unclean_id = tz_id
+        tz_id = self.clean_timezone_id(tz_id)
+        tz = self.__provider.timezone(tz_id)
         if tz is not None:
             return tz
-        if id in WINDOWS_TO_OLSON:
-            tz = self.__provider.timezone(WINDOWS_TO_OLSON[id])
-        return tz or self.__provider.timezone(_unclean_id) or self.__tz_cache.get(id)
+        if tz_id in WINDOWS_TO_OLSON:
+            tz = self.__provider.timezone(WINDOWS_TO_OLSON[tz_id])
+        return tz or self.__provider.timezone(_unclean_id) or self.__tz_cache.get(tz_id)
 
     def uses_pytz(self) -> bool:
         """Whether we use pytz at all."""