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[remkop]

• options vs positional parameters
• standalone options are booleans
• options can take parameters
• parameters are strongly typed
• built-in type converters
• registering custom type converters
• option short form
• short form options can be grouped
• last option in a short option group can take a parameter
• varargs
• optional parameters
• use arity to specify number of required parameters
  (Only allows min, consider supporting max also)
• option parameters are separated from option name or attached with configurable separator '='