# File lib/mixlib/config.rb, line 209
    def config_context(symbol, &block)
      context = Class.new
      context.extend(::Mixlib::Config)
      context.config_parent = self
      config_contexts << context
      if block
        context.instance_eval(&block)
      end
      configurable(symbol).defaults_to(context).writes_value do |value|
        raise "config context #{symbol} cannot be modified"
      end
    end