Expand allows you to return additional fields that are not included in the default fields (comma-separated list).
Supported fields:
app_last_login_ts: Timestamp of last login via the mobile app
created_ts: User creation timestamp
icon: Profile icon
invite_created_ts: Timestamp when the invite was created
invite_sent: Timestamp when the invite was last sent (0 if never)
last_login_ts: Timestamp of last login (web or app)
modified_ts: Last modification timestamp