def _open(filename, mode='r', buffering=0):
    """read only version of open()"""
    if mode not in ('r', 'rb', 'rU'):
        raise RuntimeError("Invalid open file mode, must be 'r', 'rb', or 'rU'")
    if buffering > MAX_OPEN_BUFFER:
        raise RuntimeError("Invalid buffering value, max buffer size is {}".format(MAX_OPEN_BUFFER))
    return open(filename, mode, buffering)
def _open ( filename , mode = 'r' , buffering = 0 ) : if mode not in ( 'r' , 'rb' , 'rU' ) : raise RuntimeError ( "Invalid open file mode, must be 'r', 'rb', or 'rU'" ) if buffering > MAX_OPEN_BUFFER : raise RuntimeError ( "Invalid buffering value, max buffer size is {}" . format ( MAX_OPEN_BUFFER ) ) return open ( filename , mode , buffering )
read only version of open()