code: func (ps *ParallelState) WithCatchers(catch ...*TaskCatch) *ParallelState {
  	if ps.Catchers == nil {
  		ps.Catchers = make([]*TaskCatch, 0)
  	}
  	ps.Catchers = append(ps.Catchers, catch...)
  	return ps
  }
docs: // WithCatchers is the fluent builder for TaskState