human
Complete this python program:
def _new_mem_buf(buffer=None):
assistant
#Here is the Python code you requested.

    """Allocate a new OpenSSL memory BIO.
    Arrange for the garbage collector to clean it up automatically.
    :param buffer: None or some bytes to use to put into the BIO so that they
    can be read out.
    """
    if (buffer is None):
        bio = _lib.BIO_new(_lib.BIO_s_mem())
        free = _lib.BIO_free
    else:
        data = _ffi.new('char[]', buffer)
        bio = _lib.BIO_new_mem_buf(data, len(buffer))
        def free(bio, ref=data):
            return _lib.BIO_free(bio)
    if (bio == _ffi.NULL):
        _raise_current_error()
    bio = _ffi.gc(bio, free)
    return bio