Incorrect Lua function signature in set_then_get examples

[Aryex]

Page

src/content/docs/how-to/load-and-execute-functions.mdx (Load and Execute Functions)

Problem

The set_then_get Lua example registers the function with named parameters:

#!lua name=example_module
server.register_function('set_then_get', function(key, value)
   server.call('SET', key, value)
   return server.call('GET', key)
end)

Valkey Functions always invoke a registered function with exactly two
arguments — keys (array) and args (array). So key binds to the whole
keys array and value to the whole args array (both Lua tables), not
strings. When called as fcall("set_then_get", keys: ["page:home:visits"], args: ["1"]), the function runs server.call('SET', <table>, <table>) and
the server rejects it:

ResponseError: Command arguments must be strings or integers

The client-side fcall/function_load calls are correct — the bug is only
in the Lua function body.

Scope

This same broken signature appears in all language tabs on the page
(Python, Java, Node, Go, PHP, C#, Ruby). The other example on the page,
update_visits, uses the correct array-indexing style and works.

Suggested fix

Use the (keys, args) signature and index into the arrays, across every
language tab:

#!lua name=example_module
server.register_function('set_then_get', function(keys, args)
   server.call('SET', keys[1], args[1])
   return server.call('GET', keys[1])
end)

How it was found

Caught while verifying Ruby doc examples against the published
valkey-glide-rb 1.0.0.pre.rc2 gem with a live Valkey server (PRs #299/#300).