[HttpResponse]|[nil] response, [string] error = snetwork.filepost(url, saveFilepath, body, headers, method, progressCallback, files)
        
        
Performs a POST web request synchronously.
Parameters
                saveFilepath
stringThe file path to save the response body to.
 
                body
stringThe body of the request.
 
                progressCallback
nil | "
fun(downloadDone:integer,downloadTotal:integer, uploadDone:integer, uploadTotal:integer) A function which will be called whenever progress is made on the request.
 
        Return Value
                error
stringThe error message if the request failed.