由trend trend_type换算cmd

    @staticmethod
    def format_getcmd(trend,trend_type):
        cmd = ''
        if trend == 0:
            if trend_type == 0:
                cmd = 'buy limit'
            elif trend_type == 1:
                cmd = 'buy stop'
            elif trend_type == 3:
                cmd = 'buy'
        elif trend == 1:
            if trend_type == 0:
                cmd = 'sell limit'
            elif trend_type == 1:
                cmd = 'sell stop'
            elif trend_type == 3:
                cmd = 'sell'
        return cmd