checking if CVar exists

[CrittenxD]

Yo, I've been looking for a while and I haven't found something. I simply want to check if a cvar actually exists in case some get removed before Classic release. The following example produces an error if the cvar doesnt exist:

function setcvarifexists(cvar, value)
if GetCVarDefault(cvar) then SetCVar(cvar, value)
end
end

I'm looking for a replacement for GetCVarDefault(cvar) which just checks if the cvar exists.

EDIT: I'm also looking for a command to update all cvars similar to RestartGx(). For example the Timestamp setting will only load after reloading ui.