code: func (im *imp) auth(ctx *importer.SetupContext) (*oauth2.Config, error) {
  	baseURL, err := url.Parse(ctx.AccountNode.Attr(acctAttrInstanceURL))
  	if err != nil {
  		return nil, err
  	}
  
  	tokenURL := *baseURL
  	tokenURL.Path = path.Join(tokenURL.Path, tokenPath)
  
  	authURL := *baseURL
  	authURL.Path = path.Join(authURL.Path, authorizationPath)
  
  	return &oauth2.Config{
  		ClientID:     ctx.AccountNode.Attr(acctAttrClientID),
  		ClientSecret: ctx.AccountNode.Attr(acctAttrClientSecret),
  		RedirectURL:  im.RedirectURL(im, ctx),
  		Endpoint: oauth2.Endpoint{
  			AuthURL:  authURL.String(),
  			TokenURL: tokenURL.String(),
  		},
  	}, nil
  }
docs: // auth returns the appropriate oauth2.Config for this account