# File lib/cft/commands.rb, line 28
            def require_session(errs)
                define_method(:create_session) do |argv, global_opts|
                    if argv.size < 1
                        $stderr.puts "Missing session name"
                        $stderr.puts opts
                        return nil
                    else
                        s = Cft::Session.new(argv.shift, 
                                             global_opts[:session_dir])
                        if errs[:active] && s.active?
                            $stderr.puts "Session #{s.name}: #{errs[:active]}"
                            return nil
                        elsif errs[:inactive] && ! s.active?
                            $stderr.puts "Session #{s.name}: #{errs[:inactive]}"
                            return nil
                        elsif errs[:missing] && ! s.exist?
                            $stderr.puts "Session #{s.name}: #{errs[:missing]}"
                            return nil
                        end
                        return s
                    end
                end
            end