h = c("X-AG-Access-Token" = key , "Content-Type" = "text/raw" , "outputformat" = "application/json; charset=utf-8") b<-list(body=upload_file("test.txt"))

POST(url=api ,add_headers(.headers=h) ,accept_json() ,encode = "multipart" ,body=text ,verbose())

I've been working with this code for a few days and would greatly appreciate any help!