How do I get all instances of certain class?

I am trying to get all the PointLights in a model. They are embedded in model in a model in a model, etc.

Here is my current code. I want lights array to be all the PointLights. named PointLight.

local lights = {}
local children = house:GetChildren()
for i = 1, #children do
    if children[i].Name == "PointLight" then
		lights.append(children[i])
	end
end

On a side note is .append() a real thing in LUA? (I have not tested it because I cannot get there)

children is contains just the direct descendants of house

Just loop through the children in the model and check if they inherit the "PointLight" class, like so.

local lights = {}

for i, child in pairs(house:GetChildren()) do
	if child:IsA("PointLight") then
		table.insert(light, child) -- insert `child` into the table `light`.
	end
end