Try all possible methods in download.file() (e.g.,
libcurl, curl, wget, and wininet) and see if any
method can succeed. The reason to enumerate all methods is that sometimes the
default method does not work, e.g.,
https://stat.ethz.ch/pipermail/r-devel/2016-June/072852.html.
download_file(url, output = url_filename(url), ...)The URL of the file.
Path to the output file. By default, it is determined by
url_filename().
Other arguments to be passed to download.file()
(except method).
The integer code 0 for success, or an error if none of the
methods work.