adb forward --list
        TODO: not tested

def forward_list(self):
        '''
        adb forward --list
        TODO: not tested
        '''
        version = self.version()
        if int(version[1]) <= 1 and int(version[2]) <= 0 and int(version[3]) < 31:
            raise EnvironmentError("Low adb version.")
        lines = self.run_cmd("forward", "--list").strip().splitlines()
        return [line.strip().split() for line in lines]