<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def cmd_fw(self, args):
        '''execute command defined in args'''
        if len(args) == 0:
            print(self.usage())
            return
        rest = args[1:]
        if args[0] == "manifest":
            self.cmd_fw_manifest(rest)
        elif args[0] == "list":
            self.cmd_fw_list(rest)
        elif args[0] == "download":
            self.cmd_fw_download(rest)
        elif args[0] in ["help","usage"]:
            self.cmd_fw_help(rest)
        else:
            print(self.usage())