<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def global_validate(self):
 """ Validate only global section. The options in global section is used by other private methods of ConfigReader. So, validate only global section at first. "raw_spec" is configspec for global section. "functions" is passed as an argument in "validate.Validator". about "functions" 'name': <function object> 'name':used in configspec. Same meaning as "string", "integer" and "float" in validate.py. <function object>: function which is determine by the 'name'. e.g: the contents of ConfigSpec File [hoge] ham = egg(default=fuga) Functions functions = { 'egg': is_egg } When validation, 'is_egg' function is called for ham option. """


        raw_spec = (
            "[global]",
            "user = user(default=bbd)",
            "group = group(default=bbd)",
            "log_file = log(default=/var/log/blackbird/blackbird.log)",
            "log_level = log_level(default='info')",
            "log_format = log_format(default='ltsv')",
            "max_queue_length = integer(default=32767)",
            "lld_interval = integer(default=600)",
            "interval = integer(default=60)"
        )

        functions = {
            'user': is_user,
            'group': is_group,
            'dir': extend_is_dir,
            'log': is_log,
            'log_level': is_log_level,
            'log_format': is_log_format
        }

        validator = validate.Validator(functions=functions)
        spec = self._configobj_factory(infile=raw_spec,
                                       _inspec=True
                                       )
        self.config.configspec = spec
        result = self.config.validate(validator, preserve_errors=True)
        self._parse_result(result)

        self.config['global'].configspec = None