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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 is_reseller_admin(self, req, admin_detail=None):
 """Returns True if the admin specified in the request represents a .reseller_admin. :param req: The swob.Request to check. :param admin_detail: The previously retrieved dict from :func:`get_admin_detail` or None for this function to retrieve the admin_detail itself. :param returns: True if .reseller_admin. """

        req.credentials_valid = False
        if self.is_super_admin(req):
            return True
        if not admin_detail:
            admin_detail = self.get_admin_detail(req)
        if not self.credentials_match(admin_detail,
                                      req.headers.get('x-auth-admin-key')):
            return False
        req.credentials_valid = True
        return '.reseller_admin' in (g['name'] for g in admin_detail['groups'])