code: func NewOAuthSession(clientID, clientSecret, useragent, redirectURL string) (*OAuthSession, error) {
  	o := &OAuthSession{}
  
  	if len(useragent) > 0 {
  		o.UserAgent = useragent
  	} else {
  		o.UserAgent = "Geddit Reddit Bot https://github.com/jzelinskie/geddit"
  	}
  
  	// Set OAuth config
  	o.OAuthConfig = &oauth2.Config{
  		ClientID:     clientID,
  		ClientSecret: clientSecret,
  		Endpoint: oauth2.Endpoint{
  			AuthURL:  "https://www.reddit.com/api/v1/authorize",
  			TokenURL: "https://www.reddit.com/api/v1/access_token",
  		},
  		RedirectURL: redirectURL,
  	}
  	// Inject our custom HTTP client so that a user-defined UA can
  	// be passed during any authentication requests.
  	c := &http.Client{}
  	c.Transport = &transport{http.DefaultTransport, o.UserAgent}
  	o.ctx = context.WithValue(context.Background(), oauth2.HTTPClient, c)
  	return o, nil
  }
docs: // NewOAuthSession creates a new session for those who want to log into a
  // reddit account via OAuth.