class Holder
    @@var = 99
    def Holder.var=(val)
        @@var = val
    end
    def Holder.read_var
        @@var
    end
    def var
        @@var
    end
end

@@var = "top level variable"

a = Holder.new
puts "a.var: #{a.var}"
Holder.var = 123
puts "a.var: #{a.var}"

def a.get_var
    @@var
end

puts "a.get_var: #{a.get_var}"
puts "@@var: #{@@var}"
puts "Holder.read_var: #{Holder.read_var}"