def header_property(wsgi_name):
 def fget(self):
  try:
   return (self.env[wsgi_name] or None)
  except KeyError:
   return None
 return property(fget)

def header_property ( wsgi_name ) : def fget ( self ) : try : return ( self . env [ wsgi_name ] or None ) except KeyError : return None return property ( fget )
creates a read-only header property .