def vars_by_configs
      vars = {}
      configs.each do |c|
        vars = c.values.map { |k, v| [k, c] }.to_h.merge(vars)
      end
      vars
    end
def vars_by_configs
      vars = {}
      configs.each do |c|
        vars = c.values.map { |k, v| [k, c] }.to_h.merge(vars)
      end
      vars
    end
Gets all config variables as a hash, but the hash's values are the Config instances which defines the highest
 priority of each var, instead of the var's value itself.