I'm trying to do a HTTP POST and can't figure out how to send the postdata.

Doc http://www.tecgraf.puc-rio.br/~diego/pro.../http.html
states "source: simple LTN12 source to provide the request body. If there is a body, you need to provide an appropriate "content-length" request header field, or the function will attempt to send the body as "chunked" (something few servers support). Defaults to the empty source;"

I just want to send a simple string, something like ltn12.source.xxxx(postdata), but can't figure out what xxxx should be.

Any direction would be greatly appreciated.