i saw some example code for finding members of list. so i changed it slightly and converged for fit to me, however it doesn't work
screen_name <-"Newsminster"
api.url <- paste0("https://api.twitter.com/1.1/lists/list.json?","screen_name=", screen_name)
url.get=GET(api.url)
url.content=content(url.get, as="text")
output :
url.content [1] "{\"errors\":[{\"code\":215,\"message\":\"Bad Authentication data.\"}]}"