class Regexp::Expression::Sequence

def quantify(token, text, min = nil, max = nil, mode = :greedy)
  offset = -1
  target = expressions[offset]
  while target.is_a?(FreeSpace)
    target = expressions[offset -= 1]
  end
  target || raise(ArgumentError, "No valid target found for '#{text}' "\
                                 'quantifier')
  target.quantify(token, text, min, max, mode)
end