#!/usr/bin/env ruby
$: << File.expand_path('lib')

require 'cl'

class Add < Cl::Cmd
  opt '--to GROUP', enum: %w(one two)

  def run
    p to
  end
end

Cl.new('owners').run(%w(add --to one))

# Output:
#
#   "one"

Cl.new('owners').run(%w(add --to unknown))

# Unknown value: to=unknown (known values: one, two)
#
# Usage: enum add [options]
#
# Options: ...