greenlet.py: fix formatting

gevent/greenlet.py

@@ -3,6 +3,7 @@ import os
 import traceback
 from gevent import core
 
+
 __all__ = ['getcurrent',
            'TimeoutError',
            'Timeout',
@@ -15,6 +16,7 @@ __all__ = ['getcurrent',
            'with_timeout',
            'fork']
 
+
 try:
     from py.magic import greenlet
     Greenlet = greenlet
@@ -27,6 +29,7 @@ GreenletExit = greenlet.GreenletExit
 MAIN = greenlet.getcurrent()
 _threadlocal = None
 
+
 class TimeoutError(Exception):
     """Exception raised if an asynchronous operation times out"""
 
@@ -162,7 +165,6 @@ def signal(signalnum, handler, *args, **kwargs):
     return core.signal(signalnum, deliver_exception_to_MAIN)
 
 
-
 def get_hub():
     global _threadlocal
     try: