<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def site_name(self, site_name):
 """Sets api_version and hash_string. Parameters: site_name (str):
 The site name in 'SITE_LIST', default sites. Raises: PybooruError: When 'site_name' isn't valid. """

        # Set base class property site_name
        _Pybooru.site_name.fset(self, site_name)

        if ('api_version' and 'hashed_string') in SITE_LIST[site_name]:
            self.api_version = SITE_LIST[site_name]['api_version']
            self.hash_string = SITE_LIST[site_name]['hashed_string']