class Selenium::WebDriver::Support::Select

def deselect_by_index(index)
  raise Error::UnsupportedOperationError, 'you may only deselect option of a multi-select' unless multiple?
  opts = find_by_index index
  return deselect_option(opts.first) unless opts.empty?
  raise Error::NoSuchElementError, "cannot locate option with index: #{index}"
end