    # File lib/chef/provider/env.rb, line 123
          def action_modify
            if @key_exists
              if compare_value
                modify_env
                Chef::Log.info("#{@new_resource} modified")
                @new_resource.updated_by_last_action(true)
              end
            else
              raise Chef::Exceptions::Env, "Cannot modify #{@new_resource} - key does not exist!"
            end
          end