def extend_system_path(paths):
 old_PATH = compat.getenv('PATH', '')
 paths.append(old_PATH)
 new_PATH = os.pathsep.join(paths)
 compat.setenv('PATH', new_PATH)

def extend_system_path ( paths ) : old_PATH = compat . getenv ( 'PATH' , '' ) paths . append ( old_PATH ) new_PATH = os . pathsep . join ( paths ) compat . setenv ( 'PATH' , new_PATH )
add new paths at the beginning of environment variable path .