def tt_check_all(kb, alpha, symbols, model):
if not symbols:<EOL><INDENT>if pl_true(kb, model):<EOL><INDENT>result = pl_true(alpha, model)<EOL>assert result in (True, False)<EOL>return result<EOL><DEDENT>else:<EOL><INDENT>return True<EOL><DEDENT><DEDENT>else:<EOL><INDENT>P, rest = symbols[<NUM_LIT:0>], symbols[<NUM_LIT:1>:]<EOL>return (tt_check_all(kb, alpha, rest, extend(model, P, True)) and<EOL>tt_check_all(kb, alpha, rest, extend(model, P, False)))<EOL><DEDENT>
Auxiliary routine to implement tt_entails.