get requirements from whl code example

Example: install pip

python -m pip download [options] <requirement specifier> [package-index-options] ...
python -m pip download [options] -r <requirements file> [package-index-options] ...
python -m pip download [options] <vcs project url> ...
python -m pip download [options] <local project path> ...
python -m pip download [options] <archive url/path> ...