code: func (Pipe) Default(ctx *context.Context) error {
  	var ids = map[string]int{}
  	for i, build := range ctx.Config.Builds {
  		ctx.Config.Builds[i] = buildWithDefaults(ctx, build)
  		ids[ctx.Config.Builds[i].ID]++
  	}
  	if len(ctx.Config.Builds) == 0 {
  		ctx.Config.Builds = []config.Build{
  			buildWithDefaults(ctx, ctx.Config.SingleBuild),
  		}
  	}
  	for id, cont := range ids {
  		if cont > 1 {
  			return fmt.Errorf("found %d builds with the ID '%s', please fix your config", cont, id)
  		}
  	}
  	return nil
  }
docs: // Default sets the pipe defaults