Cannot Initialize Object in Ruby

I am trying to initialize an object in Ruby, but I get an error: "undefined method `Thing’ for main:Object (NoMethodError)"

However, isn’t that what the initialize method is for?

class Thing
  def initialize(id, color)
    @id = id
    @color = color
  end
end

Thing thing = Thing.new(1, "blue")

>Solution :

Local variables are created by simply assigning to them. You don’t have to declare them or specify their type. (in fact, you can’t)

Just write:

thing = Thing.new(1, "blue")