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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add(self, key, value):
 """Add CLI Arg to lists value. Args: key (string):
 The CLI Args key (e.g., --name). value (string):
 The CLI Args value (e.g., bob). """

        if isinstance(value, list):
            # TODO: support env vars in list w/masked values
            for val in value:
                self._add_arg_python(key, val)
        elif isinstance(value, dict):
            err = 'Dictionary types are not currently supported for field.'
            print('{}{}{}'.format(c.Style.BRIGHT, c.Fore.RED, err))
        else:
            mask = False
            env_var = re.compile(r'^\$env\.(.*)$')
            envs_var = re.compile(r'^\$envs\.(.*)$')

            if env_var.match(str(value)):
                # read value from environment variable
                env_key = env_var.match(str(value)).groups()[0]
                value = os.environ.get(env_key, value)
            elif envs_var.match(str(value)):
                # read secure value from environment variable
                env_key = envs_var.match(str(value)).groups()[0]
                value = os.environ.get(env_key, value)
                mask = True
            self._add_arg(key, value, mask)