def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def test_ccode_sqrt():
    assert ccode(sqrt(x)) == "sqrt(x)"
    assert ccode(x**0.5) == "sqrt(x)"
    assert ccode(sqrt(x)) == "sqrt(x)"