downsample-fits --version (return code: 0)
downsample-fits: invalid option -- '-'
downsample-fits [options] <input-file> <output-file>
use "-" to write to stdout.
[-s <scale>]: downsample scale (default: 2): integer
[-e <extension>]: read extension (default: 0)
[-v]: verbose
downsample-fits --help (return code: 0)
downsample-fits: invalid option -- '-'
downsample-fits [options] <input-file> <output-file>
use "-" to write to stdout.
[-s <scale>]: downsample scale (default: 2): integer
[-e <extension>]: read extension (default: 0)
[-v]: verbose