FromString returns an Enum corresponding to the string parameter This method is intended to be used from validated input.

Parse returns an Enum corresponding to the string parameter If the string doesn't correspond to any Enum, returns an error (nil otherwise) This function is intended to be used to parse user input.

Add represents an add action, to install a feature.

Check represents a check action, to test if a feature is installed.

Remove represents a remove action, to remove a feature.

Enum is the type of an action.