Build a booking assistant that remembers "which step it's on." Once you save the progress step, it carries over when you ask again on the next turn. Complete advance_step and current_step. Note: uses google-adk session state. advance_step(service, app_name, user_id, session_id, step) saves the step and returns the updated session. current_step(service, app_name, user_id, session_id) returns the current step, or 0 when none is saved.
This challenge asks you to build two helper functions that keep a booking progress step across conversation turns using google-adk per-conversation state. One function saves the current step and the other retrieves it. The saved step must carry over so the next turn sees it.
A google-adk agent carries per-conversation state that persists across turns, and values you need to remember from one turn to the next live in that state. This problem exercises how you write to that state and whether you read it back to confirm the value. Getting into the habit of checking that a saved value still shows up on a later turn is an important part of working with ADK state.