Report E302 for blank lines before an "async def"

pycodestyle.py

@@ -250,10 +250,12 @@ def blank_lines(logical_line, blank_lines, indent_level, line_number,
     Use blank lines in functions, sparingly, to indicate logical sections.
 
     Okay: def a():\n    pass\n\n\ndef b():\n    pass
+    Okay: def a():\n    pass\n\n\nasync def b():\n    pass
     Okay: def a():\n    pass\n\n\n# Foo\n# Bar\n\ndef b():\n    pass
 
     E301: class Foo:\n    b = 0\n    def bar():\n        pass
     E302: def a():\n    pass\n\ndef b(n):\n    pass
+    E302: def a():\n    pass\n\nasync def b(n):\n    pass
     E303: def a():\n    pass\n\n\n\ndef b(n):\n    pass
     E303: def a():\n\n\n\n    pass
     E304: @decorator\n\ndef a():\n    pass
@@ -266,7 +268,7 @@ def blank_lines(logical_line, blank_lines, indent_level, line_number,
             yield 0, "E304 blank lines found after function decorator"
     elif blank_lines > 2 or (indent_level and blank_lines == 2):
         yield 0, "E303 too many blank lines (%d)" % blank_lines
-    elif logical_line.startswith(('def ', 'class ', '@')):
+    elif logical_line.startswith(('def ', 'async def', 'class ', '@')):
         if indent_level:
             if not (blank_before or previous_indent_level < indent_level or
                     DOCSTRING_REGEX.match(previous_logical)):

testsuite/E30.py

@@ -44,7 +44,13 @@ def a():
 def b():
     pass
 #:
+#: E302:4:1
+def a():
+    pass
 
+async def b():
+    pass
+#:
 
 #: E303:5:1
 print