def parse_set_header(value, on_update=None):
 if (not value):
  return HeaderSet(None, on_update)
 return HeaderSet(parse_list_header(value), on_update)

def parse_set_header ( value , on_update = None ) : if ( not value ) : return HeaderSet ( None , on_update ) return HeaderSet ( parse_list_header ( value ) , on_update )
parse a set-like header and return a :class:~werkzeug .