'type' object is not subscriptable

edit

I have a node that is a service that lists wifi access points and their details. When I first run rosrun there's no errors. Then I make a service request and it says Error processing request: 'type' object is not subscriptable. I'm sure it's a basic Python error but I can't figure out what it is. Thanks!

The relevant code:

    ssid_list.append(ssid)
    strength_list.append(strength)
    secured_list.append(secured)

  return WifiListResponse[String(ssid_list), UInt8(strength_list), Bool(secured_list)]

my .srv file:

int8 request
---
string[] ssid_list
uint8[] strength_list
bool[] secured_list