Contains error messages or matched argument lists for each option, also storing number of arguments that failed to match and excess arguments.
Contains error messages or matched argument lists for each option, also storing number of arguments that failed to match and excess arguments.
Also defines ordering for selecting best-match failure from list of failures.
Run parse.
Run parse.
arguments to parse
list of (converter, invocation, required flag)
Parses the trailing arguments (including the arguments to last option). Uses simple backtraking algorithm.