Using httr in R to establish an implicit Oauth2 flow with StackOverflow.com

I am trying to establish an "implicit" Oauth2 authorization flow for my test connect in R to StackOverflow via the StackExchange API.

I am in situation #3 of this related post, that specifies how to set the redirect_uri and other values in a lanugage-agnostic way.

I've taken the steps described, namely setting up the app on StackApps.com to enable implicit authentication.

I've replicated the linked instructions in R with the httr library, the only major adaptation is that apparently httr requires the client secret earlier in the process than StackOverflow actually requires it.

library(httr)

# in the StackApps answer stackoverflow.com was used here.
# that just took me to the landing page.

# the docs use this URI and it gets me closer but 
# it just says "Authorizing Application" with a blank page under that
#   and it never completes.
end <- oauth_endpoint(authorize   = "stackoverflow.com/oauth", 
                           access = "stackoverflow.com/oauth")


client_secret = "secret_code_here"

myapp <- oauth_app("myapp",
                   key    = "12665", # not a secret
                   secret = client_secret,
                   redirect_uri="https://stackexchange.com/oauth/login_success")


token <- oauth2.0_token(end,
                        myapp,
                        scope=NULL)
                        #,use_oob=T)

When I run my code a browser automatically opens and goes to StackOverflow.com. However, it just takes me to the landing page and Oauth never completes.

I tried it with use_oob=T and the only difference was that R prompted me for an authorization code that was never provided.