class Coupdoeil::Popover::Option::Placement

def validate!
  values = value.to_s.split(",")
  values.each do |placement_value|
    next if placement_value.strip.in?(VALUES)
    values_sentence = VALUES.to_sentence(last_word_connector: " or ")
    raise_invalid_option "Value must be one of: #{values_sentence}"
  end
end