Update coding style after pycodestyle 2.1.0

In pycodestyle 2.1.0, E305 was introduced, which requires two blank
lines after top level declarations, too.

See https://github.com/PyCQA/pycodestyle/issues/400

See also #10689; thanks @stepshal for first mentioning this issue and
initial patches

youtube_dl/__init__.py

@@ -449,4 +449,5 @@ def main(argv=None):
     except KeyboardInterrupt:
         sys.exit('\nERROR: Interrupted by user')
 
+
 __all__ = ['main', 'YoutubeDL', 'gen_extractors', 'list_extractors']

youtube_dl/aes.py

@@ -174,6 +174,7 @@ def aes_decrypt_text(data, password, key_size_bytes):
 
     return plaintext
 
+
 RCON = (0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36)
 SBOX = (0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
         0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
@@ -328,4 +329,5 @@ def inc(data):
             break
     return data
 
+
 __all__ = ['aes_encrypt', 'key_expansion', 'aes_ctr_decrypt', 'aes_cbc_decrypt', 'aes_decrypt_text']

youtube_dl/compat.py

@@ -2491,6 +2491,7 @@ class _TreeBuilder(etree.TreeBuilder):
     def doctype(self, name, pubid, system):
         pass
 
+
 if sys.version_info[0] >= 3:
     def compat_etree_fromstring(text):
         return etree.XML(text, parser=etree.XMLParser(target=_TreeBuilder()))
@@ -2787,6 +2788,7 @@ def workaround_optparse_bug9161():
             return real_add_option(self, *bargs, **bkwargs)
         optparse.OptionGroup.add_option = _compat_add_option
 
+
 if hasattr(shutil, 'get_terminal_size'):  # Python >= 3.3
     compat_get_terminal_size = shutil.get_terminal_size
 else:

youtube_dl/downloader/external.py

@@ -293,6 +293,7 @@ class FFmpegFD(ExternalFD):
 class AVconvFD(FFmpegFD):
     pass
 
+
 _BY_NAME = dict(
     (klass.get_basename(), klass)
     for name, klass in globals().items()

youtube_dl/socks.py

@@ -103,6 +103,7 @@ class ProxyType(object):
     SOCKS4A = 1
     SOCKS5 = 2
 
+
 Proxy = collections.namedtuple('Proxy', (
     'type', 'host', 'port', 'username', 'password', 'remote_dns'))
 

youtube_dl/swfinterp.py

@@ -115,6 +115,8 @@ def _u30(reader):
     res = _read_int(reader)
     assert res & 0xf0000000 == 0
     return res
+
+
 _u32 = _read_int
 
 
@@ -176,6 +178,7 @@ class _Undefined(object):
         return 'undefined'
     __repr__ = __str__
 
+
 undefined = _Undefined()