code: func NewPerHost(defaultDialer, bypass Dialer) *PerHost {
  	return &PerHost{
  		def:    defaultDialer,
  		bypass: bypass,
  	}
  }
docs: // NewPerHost returns a PerHost Dialer that directs connections to either
  // defaultDialer or bypass, depending on whether the connection matches one of
  // the configured rules.