Issue with $at_timezone function in timetz

[gureshme]

I have come across this error in trino which is throwing error when I run query with select at_timezone(current_time,"+-4") but same thing works when I run at_timezone(current_timestamp,"+-4") or when I pass $ with argument it also works like -select at_timezone($current_time,"+-4"). I see value diff between function at_timezone in files files timetz/AtTimezone and timestamptz/AtTimezone. In timetz at_timezone function has value @ScalarFunction(value = "$at_timezone", hidden = true) whereas in timestamptz/AtTimezone there is no $ sign and hidden true. I wanted to understand the significance of $ in timetz/AtTimezone and hidden=true.

[martint]

The $at_timezone function is an internal engine function used to implement the AT TIME ZONE ... syntax. It's not meant to be used directly, and may be removed or changed in the future without notice.