argMap is option -> argument (or "" if it is a unary argument) residualArgs are what is left after removing the options and their args.
argMap is option -> argument (or "" if it is a unary argument) residualArgs are what is left after removing the options and their args.
(Since version 2.10.0) Use leftOfArrow instead
(Since version 2.10.0) Use resultOfEnsuring instead