def fetch_command(self, global_options, subcommand):
        commands = self.get_commands(global_options)
        try:
            klass = commands[subcommand]
        except KeyError:
            sys.stderr.write("Unknown command: %r\nType '%s help' for usage.\nMany commands will only run at project directory, maybe the directory is not right.\n" % \
                (subcommand, self.prog_name))
            sys.exit(1)
        return klass
Try to find a Link matching req
dataset/ETHPy150Open limodou/uliweb/uliweb/core/commands.py/CommandManager.fetch_command--crossover with--dataset/ETHPy150Open pypa/pip/pip/index.py/PackageFinder.find_requirement