$ program foo 42 true
("foo",42,True)
$ program --help
program [OPTIONS] STRING INTEGER BOOL
  -h  --help  show help and exit
$ program foo 42 bar
cannot parse as BOOL: bar
# exit-code 1
$ program
missing argument of type STRING
missing argument of type INTEGER
missing argument of type BOOL
# exit-code 1
$ program foo 42 yes bar
unknown argument: bar
# exit-code 1