…st body data.
…efer to the request body or the query string, as appropriate. "GET parameters", "POST data", etc aren't the ideal terminology to use - they come from common usage with web browsers, rather than the HTTP specification, so are off-putting in other contexts.
…- I think this makes the code clearer, but it also prepares the way for reusing the encoding code
…ndicate that it allows bytes. Update documentation of requests.put() to refer to the "data" parameter rather than the (hidden, but functional) "params" parameter, and note that that also allows both bytes and dictionaries.