diff --git a/archivemail.py b/archivemail.py
index a575929..b98a552 100755
--- a/archivemail.py
+++ b/archivemail.py
@@ -103,8 +103,8 @@ class Stats:
                               compression extension (eg .gz)
 
         """
-        assert(mailbox_name)
-        assert(final_archive_name)
+        assert mailbox_name
+        assert final_archive_name
         self.__start_time = time.time()
         self.__mailbox_name = mailbox_name
         self.__archive_name = final_archive_name + ".gz"
@@ -326,7 +326,7 @@ class LockableMboxMixin:
 
     def lock(self):
         """Lock this mbox with both a dotlock and a posix lock."""
-        assert(not self._locked)
+        assert not self._locked
         attempt = 1
         while True:
             try:
@@ -347,7 +347,7 @@ class LockableMboxMixin:
 
     def unlock(self):
         """Unlock this mbox."""
-        assert(self._locked)
+        assert self._locked
         self._dotlock_unlock()
         self._posix_unlock()
         self._locked = False
@@ -411,7 +411,7 @@ class LockableMboxMixin:
 
     def _dotlock_unlock(self):
         """Delete the dotlock file for the 'mbox' mailbox."""
-        assert(self.mbox_file_name)
+        assert self.mbox_file_name
         lock_name = self.mbox_file_name + options.lockfile_extension
         vprint("removing lockfile '%s'" % lock_name)
         os.remove(lock_name)
@@ -425,7 +425,7 @@ class LockableMboxMixin:
     def close(self):
         """Close the mbox file"""
         vprint("closing file '%s'" % self.mbox_file_name)
-        assert(not self._locked)
+        assert not self._locked
         self.mbox_file.close()
 
 
@@ -440,7 +440,7 @@ class Mbox(mailbox.UnixMailbox, LockableMboxMixin):
         Named Arguments:
         path -- file name of the 'mbox' file to be opened
         """
-        assert(path)
+        assert path
         fd = safe_open_existing(path)
         st = os.fstat(fd)
         self.original_atime = st.st_atime
@@ -453,9 +453,9 @@ class Mbox(mailbox.UnixMailbox, LockableMboxMixin):
 
     def reset_timestamps(self):
         """Set the file timestamps to the original values"""
-        assert(self.original_atime)
-        assert(self.original_mtime)
-        assert(self.mbox_file_name)
+        assert self.original_atime
+        assert self.original_mtime
+        assert self.mbox_file_name
         os.utime(self.mbox_file_name, (self.original_atime,  \
             self.original_mtime))
 
@@ -481,7 +481,7 @@ class ArchiveMbox(LockableMboxMixin):
 
     def append(self, filename):
         """Append the content of the given file to the mbox."""
-        assert(self._locked)
+        assert self._locked
         fin = open(filename, "r")
         oldsize = os.fstat(self.mbox_file.fileno()).st_size
         try:
@@ -516,8 +516,8 @@ class TempMbox:
         msg -- rfc822 message object to be written
 
         """
-        assert(msg)
-        assert(self.mbox_file)
+        assert msg
+        assert self.mbox_file
 
         self.empty = False
         vprint("saving message to file '%s'" % self.mbox_file_name)
@@ -528,13 +528,13 @@ class TempMbox:
             msg_has_mbox_format = False
             unix_from = make_mbox_from(msg)
         self.mbox_file.write(unix_from)
-        assert(msg.headers)
+        assert msg.headers
         self.mbox_file.writelines(msg.headers)
         self.mbox_file.write(os.linesep)
 
         # The following while loop is about twice as fast in
         # practice to 'self.mbox_file.writelines(msg.fp.readlines())'
-        assert(options.read_buffer_size > 0)
+        assert options.read_buffer_size > 0
         linebuf = ""
         while 1:
             body = msg.fp.read(options.read_buffer_size)
@@ -606,14 +606,14 @@ class IdentityCache:
 
     def __init__(self, mailbox_name):
         """Constructor: takes the mailbox name as an argument"""
-        assert(mailbox_name)
+        assert mailbox_name
         self.mailbox_name = mailbox_name
 
     def warn_if_dupe(self, msg):
         """Print a warning message if the message has already appeared"""
-        assert(msg)
+        assert msg
         message_id = msg.get('Message-ID')
-        assert(message_id)
+        assert message_id
         if self.seen_ids.has_key(message_id):
             user_warning("duplicate message id: '%s' in mailbox '%s'" % 
                 (message_id, self.mailbox_name))
@@ -724,11 +724,11 @@ def make_mbox_from(message):
     message -- the rfc822 message object
 
     """
-    assert(message)
+    assert message
     address = guess_return_path(message)
     time_message = guess_delivery_time(message)
     date = time.localtime(time_message)
-    assert(date)
+    assert date
     date_string = time.asctime(date)
     mbox_from = "From %s %s\n" % (address, date_string)
     return mbox_from
@@ -736,7 +736,7 @@ def make_mbox_from(message):
 
 def guess_return_path(message):
     """Return a guess at the Return Path address of an rfc822 message"""
-    assert(message)
+    assert message
 
     for header in ('Return-path', 'From'):
         address_header = message.get(header)
@@ -747,13 +747,13 @@ def guess_return_path(message):
     # argh, we can't find any valid 'Return-path' guesses - just 
     # just use the current unix username like mutt does
     login = pwd.getpwuid(os.getuid())[0]
-    assert(login)
+    assert login
     return login
 
 
 def guess_delivery_time(message):
     """Return a guess at the delivery date of an rfc822 message""" 
-    assert(message)
+    assert message
     # try to guess the delivery date from various headers
     # get more desparate as we go through the array
     for header in 'Delivery-date', 'Received', 'Resent-Date', 'Date':
@@ -928,7 +928,7 @@ def is_unread(message):
 
 def sizeof_message(message):
     """Return size of message in bytes (octets)."""
-    assert(message)
+    assert message
     file_name = None
     message_size = None
     try:
@@ -955,8 +955,8 @@ def sizeof_message(message):
 
 def is_smaller(message, size):
     """Return true if the message is smaller than size bytes, false otherwise"""
-    assert(message)
-    assert(size > 0)
+    assert message
+    assert size > 0
     message_size = sizeof_message(message) 
     if message_size < size:
         vprint("message is too small (%d bytes), minimum bytes : %d" % \
@@ -1064,13 +1064,13 @@ def archive(mailbox_name):
     Arguments:
     mailbox_name -- the filename/dirname/url of the mailbox to be archived
     """
-    assert(mailbox_name) 
+    assert mailbox_name
 
     # strip any trailing slash (we could be archiving a maildir or MH format
     # mailbox and somebody was pressing <tab> in bash) - we don't want to use
     # the trailing slash in the archive name
     mailbox_name = mailbox_name.rstrip("/")
-    assert(mailbox_name) 
+    assert mailbox_name
 
     set_signal_handlers()
     os.umask(077) # saves setting permissions on mailboxes/tempfiles
@@ -1099,7 +1099,7 @@ def archive(mailbox_name):
         # create a temporary directory for us to work in securely
         tempfile.tempdir = None
         new_temp_dir = tempfile.mkdtemp('archivemail')
-        assert(new_temp_dir)
+        assert new_temp_dir
         _stale.temp_dir = new_temp_dir
         tempfile.tempdir = new_temp_dir
         vprint("set tempfile directory to '%s'" % new_temp_dir)
@@ -1139,8 +1139,8 @@ def _archive_mbox(mailbox_name, final_archive_name):
                           old messages to - appending if the archive 
                           already exists
     """
-    assert(mailbox_name)
-    assert(final_archive_name)
+    assert mailbox_name
+    assert final_archive_name
     stats = Stats(mailbox_name, final_archive_name)
     cache = IdentityCache(mailbox_name)
     original = Mbox(path=mailbox_name)
@@ -1215,9 +1215,9 @@ def _archive_mbox(mailbox_name, final_archive_name):
 
 def _archive_dir(mailbox_name, final_archive_name, type):
     """Archive a 'maildir' or 'MH' style mailbox - used by archive_mailbox()"""
-    assert(mailbox_name)
-    assert(final_archive_name)
-    assert(type)
+    assert mailbox_name
+    assert final_archive_name
+    assert type
     stats = Stats(mailbox_name, final_archive_name)
     delete_queue = []
 
@@ -1267,8 +1267,8 @@ def _archive_dir(mailbox_name, final_archive_name, type):
 
 def _archive_imap(mailbox_name, final_archive_name):
     """Archive an imap mailbox - used by archive_mailbox()"""
-    assert(mailbox_name)
-    assert(final_archive_name)
+    assert mailbox_name
+    assert final_archive_name
     import imaplib
     import cStringIO
     import getpass
@@ -1456,7 +1456,7 @@ def imap_getdelim(imap_server):
 
 def imap_get_namespace(srv):
     """Return the IMAP namespace prefixes and hierarchy delimiters."""
-    assert('NAMESPACE' in srv.capabilities)
+    assert 'NAMESPACE' in srv.capabilities
     result, response = srv.namespace()
     if result != 'OK': 
         unexpected_error("Cannot retrieve IMAP namespace; server says: '%s'" 
@@ -1637,7 +1637,7 @@ def make_archive_name(mailbox_name):
 def check_sane_destdir(dir):
     """Do a very primitive check if the given directory looks like a reasonable
     destination directory and bail out if it doesn't."""
-    assert(dir)
+    assert dir
     if not os.path.isdir(dir):
         user_error("output directory does not exist: '%s'" % dir)
     if not os.access(dir, os.W_OK):
@@ -1685,7 +1685,7 @@ def get_filename(msg):
         #    (msg from mailbox.Maildir, Python >= 2.5)
         #    File object is msg.fp._file, we do want that.
         if msg.fp.__class__ == mailbox._ProxyFile: 
-            assert(hasattr(mailbox, "_PartialFile"))
+            assert hasattr(mailbox, "_PartialFile")
             return msg.fp._file.name
         raise
 
diff --git a/test_archivemail.py b/test_archivemail.py
index 738a5c2..329bd33 100755
--- a/test_archivemail.py
+++ b/test_archivemail.py
@@ -92,12 +92,12 @@ class TestCaseInTempdir(unittest.TestCase):
 
     def setUp(self):
         if not self.temproot:
-            assert(not tempfile.tempdir)
+            assert not tempfile.tempdir
             self.temproot = tempfile.tempdir = \
                 tempfile.mkdtemp(prefix="test-archivemail")
      
     def tearDown(self):
-        assert(tempfile.tempdir == self.temproot)
+        assert tempfile.tempdir == self.temproot
         if self.temproot:
             shutil.rmtree(self.temproot)
             tempfile.tempdir = self.temproot = None
@@ -116,9 +116,9 @@ class TestMboxDotlock(TestCaseInTempdir):
         """dotlock_lock/unlock should create/delete a lockfile"""
         lock = self.mbox_name + ".lock"
         self.mbox._dotlock_lock()
-        assert(os.path.isfile(lock))
+        assert os.path.isfile(lock)
         self.mbox._dotlock_unlock()
-        assert(not os.path.isfile(lock))
+        assert not os.path.isfile(lock)
 
     def testDotlockingSucceedsUponEACCES(self):
         """A dotlock should silently be omitted upon EACCES."""
@@ -192,7 +192,7 @@ class TestMboxNext(TestCaseInTempdir):
         mbox = archivemail.Mbox(self.not_empty_name)
         for count in range(18):
             msg = mbox.next()
-            assert(msg)
+            assert msg
         msg = mbox.next()
         self.assertEqual(msg, None)
 
@@ -214,7 +214,7 @@ class TestTempMboxWrite(TestCaseInTempdir):
             mbox_write.write(msg)
         mbox_read.close()
         mbox_write.close()
-        assert(filecmp.cmp(read_file, write_file, shallow=0))
+        assert filecmp.cmp(read_file, write_file, shallow=0)
 
     def testWriteNone(self):
         """calling mbox.write() with no message should raise AssertionError"""
@@ -229,9 +229,9 @@ class TestTempMboxRemove(TestCaseInTempdir):
 
     def testMboxRemove(self):
         """remove() should delete a mbox mailbox"""
-        assert(os.path.exists(self.mbox_name))
+        assert os.path.exists(self.mbox_name)
         self.mbox.remove()
-        assert(not os.path.exists(self.mbox_name))
+        assert not os.path.exists(self.mbox_name)
 
 
 
@@ -289,27 +289,27 @@ class TestOptionParser(unittest.TestCase):
     def testOptionPreserveUnread(self):
         """--preserve-unread option is parsed correctly"""
         archivemail.options.parse_args(["--preserve-unread"], "")
-        assert(archivemail.options.preserve_unread)
+        assert archivemail.options.preserve_unread
         archivemail.options.preserve_unread = 0
         archivemail.options.parse_args(["-u"], "")
-        assert(archivemail.options.preserve_unread)
+        assert archivemail.options.preserve_unread
 
     def testOptionSuffix(self):
         """--suffix and -s options are parsed correctly"""
         for suffix in ("_static_", "_%B_%Y", "-%Y-%m-%d"):
             archivemail.options.parse_args(["--suffix="+suffix], "")
-            assert(archivemail.options.archive_suffix == suffix)
+            assert archivemail.options.archive_suffix == suffix
             archivemail.options.suffix = None
             archivemail.options.parse_args(["-s", suffix], "")
-            assert(archivemail.options.archive_suffix == suffix)
+            assert archivemail.options.archive_suffix == suffix
 
     def testOptionDryrun(self):
         """--dry-run option is parsed correctly"""
         archivemail.options.parse_args(["--dry-run"], "")
-        assert(archivemail.options.dry_run)
+        assert archivemail.options.dry_run
         archivemail.options.preserve_unread = 0
         archivemail.options.parse_args(["-n"], "")
-        assert(archivemail.options.dry_run)
+        assert archivemail.options.dry_run
 
     def testOptionDays(self):
         """--days and -d options are parsed correctly"""
@@ -322,12 +322,12 @@ class TestOptionParser(unittest.TestCase):
     def testOptionDelete(self):
         """--delete option is parsed correctly"""
         archivemail.options.parse_args(["--delete"], "")
-        assert(archivemail.options.delete_old_mail)
+        assert archivemail.options.delete_old_mail
 
     def testOptionCopy(self):
         """--copy option is parsed correctly"""
         archivemail.options.parse_args(["--copy"], "")
-        assert(archivemail.options.copy_old_mail)
+        assert archivemail.options.copy_old_mail
 
     def testOptionOutputdir(self):
         """--output-dir and -o options are parsed correctly"""
@@ -341,7 +341,7 @@ class TestOptionParser(unittest.TestCase):
     def testOptionNocompress(self):
         """--no-compress option is parsed correctly"""
         archivemail.options.parse_args(["--no-compress"], "")
-        assert(archivemail.options.no_compress)
+        assert archivemail.options.no_compress
 
     def testOptionSize(self):
         """--size and -S options are parsed correctly"""
@@ -361,43 +361,43 @@ class TestIsTooOld(unittest.TestCase):
         """with max_days=360, should be true for these dates > 1 year"""
         for years in range(1, 10):
             time_msg = time.time() - (years * 365 * 24 * 60 * 60)
-            assert(archivemail.is_older_than_days(time_message=time_msg,
-                max_days=360))
+            assert archivemail.is_older_than_days(time_message=time_msg,
+                max_days=360)
 
     def testOld(self):
         """with max_days=14, should be true for these dates > 14 days"""
         for days in range(14, 360):
             time_msg = time.time() - (days * 24 * 60 * 60)
-            assert(archivemail.is_older_than_days(time_message=time_msg, 
-                max_days=14))
+            assert archivemail.is_older_than_days(time_message=time_msg,
+                max_days=14)
 
     def testJustOld(self):
         """with max_days=1, should be true for these dates >= 1 day"""
         for minutes in range(0, 61):
             time_msg = time.time() - (25 * 60 * 60) + (minutes * 60)
-            assert(archivemail.is_older_than_days(time_message=time_msg, 
-                max_days=1))
+            assert archivemail.is_older_than_days(time_message=time_msg,
+                max_days=1)
 
     def testNotOld(self):
         """with max_days=9, should be false for these dates < 9 days"""
         for days in range(0, 9):
             time_msg = time.time() - (days * 24 * 60 * 60)
-            assert(not archivemail.is_older_than_days(time_message=time_msg, 
-                max_days=9))
+            assert not archivemail.is_older_than_days(time_message=time_msg,
+                max_days=9)
 
     def testJustNotOld(self):
         """with max_days=1, should be false for these hours <= 1 day"""
         for minutes in range(0, 60):
             time_msg = time.time() - (23 * 60 * 60) - (minutes * 60)
-            assert(not archivemail.is_older_than_days(time_message=time_msg, 
-                max_days=1))
+            assert not archivemail.is_older_than_days(time_message=time_msg,
+                max_days=1)
 
     def testFuture(self):
         """with max_days=1, should be false for times in the future"""
         for minutes in range(0, 60):
             time_msg = time.time() + (minutes * 60)
-            assert(not archivemail.is_older_than_days(time_message=time_msg, 
-                max_days=1))
+            assert not archivemail.is_older_than_days(time_message=time_msg,
+                max_days=1)
 
 ########## archivemail.parse_imap_url() unit testing #################
 
@@ -469,7 +469,7 @@ class TestParseIMAPUrl(unittest.TestCase):
             self.assertEqual(result, mbstr[2])
         for mbstr in self.urls_onlywithpass: 
             url = mbstr[0][mbstr[0].find('://')+3:]
-            self.assertRaises(archivemail.UnexpectedError, 
+            self.assertRaises(archivemail.UnexpectedError,
                     archivemail.parse_imap_url, url)
 
     def tearDown(self): 
@@ -485,7 +485,7 @@ class TestArchive(TestCaseInTempdir):
     good_archive = good_mbox = None
 
     def verify(self):
-        assert(os.path.exists(self.mbox))
+        assert os.path.exists(self.mbox)
         if self.good_mbox is not None:
             assertEqualContent(self.mbox, self.good_mbox)
         else:
@@ -495,12 +495,12 @@ class TestArchive(TestCaseInTempdir):
             archive_name += ".gz"
             iszipped = True
         else:
-            assert(not os.path.exists(archive_name + ".gz"))
+            assert not os.path.exists(archive_name + ".gz")
             iszipped = False
         if self.good_archive is not None:
             assertEqualContent(archive_name, self.good_archive, iszipped)
         else:
-            assert(not os.path.exists(archive_name))
+            assert not os.path.exists(archive_name)
 
     def make_old_mbox(self, body=None, headers=None, messages=1, old_archive=False):
         """Make an old mbox, optionally an existing archive, and make a reference
@@ -601,10 +601,10 @@ This is after the ^From line"""
             msg = make_message(default_headers=headers, wantobj=True)
             date = time.strptime("2000-07-29", "%Y-%m-%d")
             archivemail.options.date_old_max = time.mktime(date)
-            assert(archivemail.should_archive(msg))
+            assert archivemail.should_archive(msg)
             date = time.strptime("2000-07-27", "%Y-%m-%d")
             archivemail.options.date_old_max = time.mktime(date)
-            assert(not archivemail.should_archive(msg))
+            assert not archivemail.should_archive(msg)
 
     def testMixed(self):
         """archiving a mixed mailbox"""
@@ -704,7 +704,7 @@ class TestArchiveMboxTimestamp(TestCaseInTempdir):
         self.verify()
 
     def verify(self):
-        assert(os.path.exists(self.mbox_name))
+        assert os.path.exists(self.mbox_name)
         new_atime = os.path.getatime(self.mbox_name)
         new_mtime = os.path.getmtime(self.mbox_name)
         self.assertAlmostEqual(self.mtime, new_mtime, utimes_precision)
@@ -725,12 +725,12 @@ class TestArchiveMboxAll(unittest.TestCase):
     def testNew(self):
         """new messages should be archived with --all"""
         self.msg = make_message(hours_old=24*179, wantobj=True)
-        assert(archivemail.should_archive(self.msg))
+        assert archivemail.should_archive(self.msg)
 
     def testOld(self):
         """old messages should be archived with --all"""
         self.msg = make_message(hours_old=24*181, wantobj=True)
-        assert(archivemail.should_archive(self.msg))
+        assert archivemail.should_archive(self.msg)
 
     def tearDown(self):
         archivemail.options.quiet = 0
@@ -746,12 +746,12 @@ class TestArchiveMboxPreserveUnread(unittest.TestCase):
     def testOldRead(self):
         """old read messages should be archived with --preserve-unread"""
         self.msg["Status"] = "RO"
-        assert(archivemail.should_archive(self.msg))
+        assert archivemail.should_archive(self.msg)
 
     def testOldUnread(self):
         """old unread messages should not be archived with --preserve-unread"""
         self.msg["Status"] = "O"
-        assert(not archivemail.should_archive(self.msg))
+        assert not archivemail.should_archive(self.msg)
 
     def tearDown(self):
         archivemail.options.quiet = 0
@@ -873,20 +873,20 @@ class TestArchiveMboxFlagged(unittest.TestCase):
         """by default, old flagged messages should not be archived"""
         msg = make_message(default_headers={"X-Status": "F"},
                 hours_old=24*181, wantobj=True)
-        assert(not archivemail.should_archive(msg))
+        assert not archivemail.should_archive(msg)
 
     def testIncludeFlaggedNew(self):
         """new flagged messages should not be archived with include_flagged"""
         msg = make_message(default_headers={"X-Status": "F"},
                 hours_old=24*179, wantobj=True)
-        assert(not archivemail.should_archive(msg))
+        assert not archivemail.should_archive(msg)
 
     def testIncludeFlaggedOld(self):
         """old flagged messages should be archived with include_flagged"""
         archivemail.options.include_flagged = 1
         msg = make_message(default_headers={"X-Status": "F"},
                 hours_old=24*181, wantobj=True)
-        assert(archivemail.should_archive(msg))
+        assert archivemail.should_archive(msg)
 
     def tearDown(self):
         archivemail.options.include_flagged = 0
@@ -964,12 +964,12 @@ class TestArchiveSize(unittest.TestCase):
     def testSmaller(self):
         """giving a size argument smaller than the message"""
         archivemail.options.min_size = self.msg_size - 1
-        assert(archivemail.should_archive(self.msg))
+        assert archivemail.should_archive(self.msg)
 
     def testBigger(self):
         """giving a size argument bigger than the message"""
         archivemail.options.min_size = self.msg_size + 1
-        assert(not archivemail.should_archive(self.msg))
+        assert not archivemail.should_archive(self.msg)
 
     def tearDown(self):
         archivemail.options.quiet = 0
@@ -989,8 +989,8 @@ class TestArchiveMboxMode(TestCaseInTempdir):
             os.chmod(self.mbox_name, mode)
             archivemail.archive(self.mbox_name)
             archive_name = self.mbox_name + "_archive.gz"
-            assert(os.path.exists(self.mbox_name))
-            assert(os.path.exists(archive_name))
+            assert os.path.exists(self.mbox_name)
+            assert os.path.exists(archive_name)
             new_mode = os.stat(self.mbox_name)[stat.ST_MODE]
             self.assertEqual(mode, stat.S_IMODE(new_mode))
             archive_mode = os.stat(archive_name)[stat.ST_MODE]
@@ -1003,8 +1003,8 @@ class TestArchiveMboxMode(TestCaseInTempdir):
             os.chmod(self.mbox_name, mode)
             archivemail.archive(self.mbox_name)
             archive_name = self.mbox_name + "_archive.gz"
-            assert(not os.path.exists(archive_name))
-            assert(os.path.exists(self.mbox_name))
+            assert not os.path.exists(archive_name)
+            assert os.path.exists(self.mbox_name)
             new_mode = os.stat(self.mbox_name)[stat.ST_MODE]
             self.assertEqual(mode, stat.S_IMODE(new_mode))
             os.remove(self.mbox_name)
@@ -1049,8 +1049,8 @@ def make_message(body=None, default_headers={}, hours_old=None, wantobj=False):
 
 def append_file(source, dest):
     """appends the file named 'source' to the file named 'dest'"""
-    assert(os.path.isfile(source))
-    assert(os.path.isfile(dest))
+    assert os.path.isfile(source)
+    assert os.path.isfile(dest)
     read = open(source, "r")
     write = open(dest, "a+")
     shutil.copyfileobj(read,write)
@@ -1059,7 +1059,7 @@ def append_file(source, dest):
 
 
 def make_mbox(body=None, headers=None, hours_old=0, messages=1):
-    assert(tempfile.tempdir)
+    assert tempfile.tempdir
     fd, name = tempfile.mkstemp()
     file = os.fdopen(fd, "w")
     for count in range(messages):
@@ -1097,18 +1097,18 @@ def make_old_archive(mailbox_name):
 def assertEqualContent(firstfile, secondfile, zipfirst=False):
     """Verify that the two files exist and have identical content. If zipfirst
     is True, assume that firstfile is gzip-compressed."""
-    assert(os.path.exists(firstfile))
-    assert(os.path.exists(secondfile))
+    assert os.path.exists(firstfile)
+    assert os.path.exists(secondfile)
     if zipfirst:
         try:
             fp1 = gzip.GzipFile(firstfile, "r")
             fp2 = open(secondfile, "r")
-            assert(cmp_fileobj(fp1, fp2))
+            assert cmp_fileobj(fp1, fp2)
         finally:
             fp1.close()
             fp2.close()
     else:
-        assert(filecmp.cmp(firstfile, secondfile, shallow=0))
+        assert filecmp.cmp(firstfile, secondfile, shallow=0)
 
 def cmp_fileobj(fp1, fp2):
     """Return if reading the fileobjects yields identical content."""