human
Solve the following python programming problem given the following code:
def _to_users(self, users_perms_and_groups, ticket) : 
    'Finds all users contained in the list of `users_perms_and_groups`
        by recursive lookup of users when a `group` is encountered.
        ' 
    ps = PermissionSystem (owners.env) 
    groups = ps.get_groups_dict () 
    def append_owners(users_perms_and_groups) : 
        for user_perm_or_group in users_perms_and_groups : 
            if (user_perm_or_group == 'authenticated') : 
                owners.update (set ((u [0] for u in self.env.get_known_users ()))) 
else : 
                if user_perm_or_group.isupper () : 
                    perm = user_perm_or_group 
                    for user in ps.get_users_with_permission (perm) : 
                        if (perm in PermissionCache (self.env, user, ticket.resource)) : 
                            owners.add (user) 
else : 
                    if (user_perm_or_group not in groups) : 
                        owners.add (user_perm_or_group) 
else : 
                        append_owners (groups [user_perm_or_group]) 
owners = set () 
    append_owners (users_perms_and_groups) 
    return sorted (owners) 

    
    

    Fix the buggy line: ps = PermissionSystem (owners.env)
assistant
#Here is Python program to fix the buggy line: ps = PermissionSystem (owners.

ps = PermissionSystem (self.env)