parses keys as starting with a dash, except single dashed digits.
parses keys as starting with a dash, except single dashed digits. All following non-dashed args are a list of values. If the list starts with non-dashed args, these are associated with the empty string: ""
Split on whitespace and then parse.
The args class does a simple command line parsing. The rules are: keys start with one or more "-". Each key has zero or more values following.